## Description 

The mutation payload can be a lot higher than a query payload, due to
the possibility of passing a large transaction data (e.g., publishing a
package). This PR adds a different check for when a mutation is
requested, and adds a `max_tx_payload_size` variable that holds the max
bytes that can be sent through a GraphQL mutation request.
The total sum of `txBytes + signatures` of all GraphQL mutation or
`txBytes` in a `dryRunTransactionBlock` query have to be below the
`max_tx_payload_size`.

The `max_tx_payload_size` is computed based on the `protocol_version ->
max_tx_bytes` and a Base64 overhead as follows:
`max_tx_bytes * 4 / 3`

## Test plan
Added several tests.
`cd crates/sui-graphql-rpc`
`cargo nextest run --features pg_integration -- test_query test_mutation
test_dry_run_transaction test_transaction_dry_run`


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## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] Indexer: 
- [ ] JSON-RPC: 
- [x] GraphQL: 
Added a `max_tx_payload_size` variable to protect against large
transaction queries. The sum of `txBytes + signatures` in all GraphQL
mutation `executeTransactionBlock` nodes or `txBytes` in
`dryRunTransactionBlock` nodes from a query have to be below the
`max_tx_payload_size`.
The `max_tx_payload_size` is computed based on the `protocol_version ->
max_tx_bytes` and a Base64 overhead as follows:
`max_tx_bytes * 4 / 3`
Added also a check that the overall query size is not larger than
`max_tx_payload_size` + `max_query_payload_size`, where
`max_query_payload_size` is the `read` part of the query.
- [ ] CLI: 
- [ ] Rust SDK:

---------

Co-authored-by: Ashok Menon <ashok@mystenlabs.com>