feat: json schema for broker api

[dandanlen]

Pull Request

Closes: PRO-xxx

Checklist

Please conduct a thorough self-review before opening the PR.

• [ ] I am confident that the code works.
• [ ] I have written sufficient tests.
• [ ] I have written and tested required migrations.
• [ ] I have updated documentation where appropriate.

Summary

Please include a succinct description of the purpose and content of the PR. What problem does it solve, and how? Link issues, discussions, other PRs, and anything else that will help the reviewer.

Non-Breaking changes

If this PR includes non-breaking changes, select the non-breaking label. On merge, CI will automatically cherry-pick the commit to a PR against the release branch.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 5.35714% with 106 lines in your changes missing coverage. Please review.

Project coverage is 71%. Comparing base (abc75f2) to head (846378b). Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
utilities/src/with_std/json_schema.rs	0%	45 Missing :warning:
api/lib/src/lib.rs	0%	23 Missing :warning:
state-chain/primitives/src/chains/assets.rs	20%	20 Missing :warning:
api/api-json-schema/src/lib.rs	0%	8 Missing :warning:
state-chain/chains/src/lib.rs	0%	5 Missing :warning:
...ne/src/state_chain_observer/client/base_rpc_api.rs	25%	3 Missing :warning:
state-chain/runtime/src/runtime_apis.rs	0%	1 Missing :warning:
utilities/src/with_std/rpc.rs	0%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #5454 +/- ## ====================================== - Coverage 71% 71% -0% ====================================== Files 494 496 +2 Lines 87659 87631 -28 Branches 87659 87631 -28 ====================================== - Hits 62668 62494 -174 - Misses 22379 22525 +146 Partials 2612 2612 ```

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