Add tx submission via ws

[preston-evans98]

Description

This PR adds a new /sequencer/txs/submit/ws to which customers can connect to stream tx submissions.

Request Format

{
  "id": 1,
  "contents": {"body": <BASE64_RAW_TX>}
}

Response Format

{ 
  "id": 1,
  "contents": { 
     "tx_hash": ...,
     "receipt", ...
     "events: [...], 
     ...
   } 
}

• I have updated CHANGELOG.md with a new entry if my PR makes any breaking changes or fixes a bug. If my PR removes a feature or changes its behavior, I provide help for users on how to migrate to the new behavior.
• I have carefully reviewed all my Cargo.toml changes before opening the PRs. (Are all new dependencies necessary? Is any module dependency leaked into the full-node (hint: it shouldn't)?)

Linked Issues

• Fixes # (issue, if applicable)
• Related to # (issue)

Testing

Describe how these changes were tested. If you've added new features, have you added unit tests?

Docs

Describe where this code is documented. If it changes a documented interface, have the docs been updated?

Rendered docs are available at https://sovlabs-ci-rustdoc-artifacts.us-east-1.amazonaws.com/<BRANCH_NAME>/index.html

[kalyan02]

Thanks for getting to this quickly. It looks good in principle. Trying to think about the message format and will share more on it shortly

[preston-evans98]

Thanks for getting to this quickly. It looks good in principle. Trying to think about the message format and will share more on it shortly

Hey @kalyan02, let me know if you've got any feedback now that you've had some time to think! We're currently planning to release this next week, but can hold off for a few more days if you need more time to consider.