cardano-rpc | Add UTxO RPC: submitTx method

[carbolymer]

Changelog

- description: |
    cardano-rpc | Add UTxO RPC: submitTx method
# uncomment types applicable to the change:
  type:
   - feature        # introduces a new feature
  # - breaking       # the API has changed in a breaking way
  # - compatible     # the API has changed but is non-breaking
  # - optimisation   # measurable performance improvements
  # - refactoring    # QoL changes
  # - bugfix         # fixes a defect
  # - test           # fixes/modifies tests
  # - maintenance    # not directly related to the code
  # - release        # related to a new release preparation
  # - documentation  # change in code docs, haddocks...
  projects:
  - cardano-rpc

Context

Tested in:

• gRPC: Add gRPC interface to cardano-node with tests in cardano-testnet cardano-node#6273

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. See Running tests for more details
• Self-reviewed the diff

[Jimbo4350]

Have you implemented something that deviates?

[carbolymer]

Yes this is a new "sum type" isomorphic to Either. Original proto file had just successful txIds without errors. https://github.com/utxorpc/spec/blob/main/proto/utxorpc/v1alpha/submit/submit.proto#L38