Improve http observer/get_tss_address

[swift1337]

GET $base/observer/get_tss_address/{btcChainId}

While exploring zeta RPCs, I noticed we have a weird way of getting TSS addresses via observer keeper.

node/x/observer/keeper/grpc_query_tss.go

Line 41 in 9df63f8

func (k Keeper) GetTssAddress(

btc_chain_id=8332
curl -s "https://zetachain.blockpi.network/lcd/v1/public/zeta-chain/observer/get_tss_address/$btc_chain_id" | jq
{
  "eth": "0x70e967acFcC17c3941E87562161406d41676FD83",
  "btc": "bc1qm24wp577nk8aacckv8np465z3dvmu7ry45el6y"
}

Proposed changes

• Caller needs to specify BTC chain id — this should be done automatically by the node
• We need to output ALL chains in a list, not only chain types

GET $base/observer/get_tss_addresses

{
  "chains": [
    {
      "id": "1",
      "tss": "0x70e967acFcC17c3941E87562161406d41676FD83"
    },
    {
      "id": "56",
      "tss": "0x70e967acFcC17c3941E87562161406d41676FD83"
    },
    {
      "id": "8332",
      "tss": "bc1qm24wp577nk8aacckv8np465z3dvmu7ry45el6y"
    },
    // ...
  ]
}