Merge bitcoin#24716: rpc: Fix documentation assertion for getrawtransaction

71038a1 rpc: Fix documentation assertion for `getrawtransaction` (laanwj)

Pull request description:

  When `getrawtransaction` is successfully used on a coinbase transaction, there is an assertion error. This is very unlikely but happens in the `interface_usdt_utxocache.py` test in bitcoin#24358.

  This does the following:

  - Add missing "coinbase" documentation.

  - Synchronize documentation between `getrawtransaction` and  `decoderawtransaction`, the two users of `TxToUniv` that have detailed   documentation. `decodepsbt` and `getblock` also uses it but fortunately elides this block.

  - Change "vout[].amount" to `STR_AMOUNT` for consistency.

  - Add maintainer comment to keep the two places synchronized. It might  be possible to get smarter with deduplication, but there are some  extra fields that prevent the obvious way.

ACKs for top commit:
  jonatack:
    ACK 71038a1

Tree-SHA512: 962236130455d805190ff9a5c971e4e25c17db35614a90ce340264ec953b0ad7fb814eb33ae430b5073955a8a350f72bdd67ba93e35f9c70e5175b836a767a35

Author: MarcoFalke

src/rpc/rawtransaction.cpp

@@ -187,6 +187,7 @@ static RPCHelpMan getrawtransaction()
                          RPCResult::Type::STR, "data", "The serialized, hex-encoded data for 'txid'"
                     },
                     RPCResult{"if verbose is set to true",
+                        // When updating this documentation, update `decoderawtransaction` in the same way.
                         RPCResult::Type::OBJ, "", "",
                         {
                             {RPCResult::Type::BOOL, "in_active_chain", /* optional */ true, "Whether specified block is in the active chain or not (only present with explicit \"blockhash\" argument)"},
@@ -199,9 +200,11 @@ static RPCHelpMan getrawtransaction()
                             {
                                 {RPCResult::Type::OBJ, "", "",
                                 {
-                                    {RPCResult::Type::STR_HEX, "txid", "The transaction id"},
-                                    {RPCResult::Type::NUM, "vout", "The output number"},
-                                    {RPCResult::Type::OBJ, "scriptSig", "The script",
+                                    {RPCResult::Type::STR_HEX, "coinbase", /*optional=*/true, "The coinbase value (only if coinbase transaction)"},
+                                    {RPCResult::Type::STR_HEX, "txid", /*optional=*/true, "The transaction id (if not coinbase transaction)"},
+                                    {RPCResult::Type::NUM, "vout", /*optional=*/true, "The output number (if not coinbase transaction)"},
+                                    {RPCResult::Type::OBJ, "scriptSig", /*optional=*/true, "The script (if not coinbase transaction)",
+                                    {
                                     {
                                         {RPCResult::Type::STR, "asm", "asm"},
                                         {RPCResult::Type::STR_HEX, "hex", "hex"},
@@ -213,13 +216,13 @@ static RPCHelpMan getrawtransaction()
                             {
                                 {RPCResult::Type::OBJ, "", "",
                                 {
-                                    {RPCResult::Type::NUM, "value", "The value in " + CURRENCY_UNIT},
+                                    {RPCResult::Type::STR_AMOUNT, "value", "The value in " + CURRENCY_UNIT},
                                     {RPCResult::Type::NUM, "n", "index"},
                                     {RPCResult::Type::OBJ, "scriptPubKey", "",
                                     {
                                         {RPCResult::Type::STR, "asm", "the asm"},
                                         {RPCResult::Type::STR, "desc", "Inferred descriptor for the output"},
-                                        {RPCResult::Type::STR, "hex", "the hex"},
+                                        {RPCResult::Type::STR_HEX, "hex", "the hex"},
                                         {RPCResult::Type::STR, "type", "The type, eg 'pubkeyhash'"},
                                         {RPCResult::Type::STR, "address", /* optional */ true, "The Dash address (only if a well-defined address exists)"},
                                     }},
@@ -742,19 +745,20 @@ static RPCHelpMan decoderawtransaction()
                 RPCResult{
                     RPCResult::Type::OBJ, "", "",
                     {
+                        // When updating this documentation, update `getrawtransaction` in the same way.
                         {RPCResult::Type::STR_HEX, "txid", "The transaction id"},
-                        {RPCResult::Type::NUM, "size", "The transaction size"},
+                        {RPCResult::Type::NUM, "size", "The serialized transaction size"},
                         {RPCResult::Type::NUM, "version", "The version"},
                         {RPCResult::Type::NUM, "type", "The type"},
                         {RPCResult::Type::NUM_TIME, "locktime", "The lock time"},
                         {RPCResult::Type::ARR, "vin", "",
                         {
                             {RPCResult::Type::OBJ, "", "",
                             {
-                                {RPCResult::Type::STR_HEX, "coinbase", /* optional */ true, ""},
-                                {RPCResult::Type::STR_HEX, "txid", /* optional */ true, "The transaction id"},
-                                {RPCResult::Type::NUM, "vout", /* optional */ true, "The output number"},
-                                {RPCResult::Type::OBJ, "scriptSig", /* optional */ true, "The script",
+                                {RPCResult::Type::STR_HEX, "coinbase", /*optional=*/true, "The coinbase value (only if coinbase transaction)"},
+                                {RPCResult::Type::STR_HEX, "txid", /*optional=*/true, "The transaction id (if not coinbase transaction)"},
+                                {RPCResult::Type::NUM, "vout", /*optional=*/true, "The output number (if not coinbase transaction)"},
+                                {RPCResult::Type::OBJ, "scriptSig", /*optional=*/true, "The script (if not coinbase transaction)",
                                 {
                                     {RPCResult::Type::STR, "asm", "asm"},
                                     {RPCResult::Type::STR_HEX, "hex", "hex"},
@@ -766,7 +770,7 @@ static RPCHelpMan decoderawtransaction()
                         {
                             {RPCResult::Type::OBJ, "", "",
                             {
-                                {RPCResult::Type::NUM, "value", "The value in " + CURRENCY_UNIT},
+                                {RPCResult::Type::STR_AMOUNT, "value", "The value in " + CURRENCY_UNIT},
                                 {RPCResult::Type::NUM, "n", "index"},
                                 {RPCResult::Type::OBJ, "scriptPubKey", "",
                                 {