Utxo JSON-RPC unit tests

[kayvank]

Create client/server servant the json-rpc test

• add a http JSON-RPC test the RPC routes and round trip payload seiralisation
• update the marconi-chain-index/exmples/json-rpc related modules for the recent changes
• separate the RPC routes from REST routes so that we may reuse the RPC handlers client code
• NOTE, there is TODO that comments a failing test till we have a fix for the ScriptData round trip serialization

• PLT-94

Pre-submit checklist:

• Branch
  • [x ] Tests are provided (if possible)
  • [ x] Commit sequence broadly makes sense
  • [x ] Key commits have useful messages
  • [ ] Formatting, PNG optimization, etc. are updated
  • [x ] Important changes are reflected in changelog.d of the affected packages
• PR
  • [x ] Self-reviewed the diff
  • [ x] Useful pull request description
  • [ ] Reference the ADR in the PR and reference the PR in the ADR (if revelant)
  • [ x] Reviewer requested

[koslambrou]

@kayvank Really sorry about the conflicts. Had to rename marconi-mamba to marconi-chain-index

[kayvank]

@kayvank Really sorry about the conflicts. Had to rename marconi-mamba to marconi-chain-indexsidechain

No problem. The name change is a natural progression considering the changes we've made recently