fix(openapi): Add defaults to rpc methods where needed

[oxarbitrage]

Motivation

Several of the rpc methods need default implementations so a sample response can be created in the openapi spec.

Solution

Add defaults where needed, complete hardcoded list of rpc methods in the openapi utility. Add a random string as the request ID.

Tests

Manually tested.

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.

[arya2]

This looks good, the only part I'm unsure about is the request_id_property type_ field being "number" when the default value is an alphanumeric.

[arya2]

This looks good!

There's a small merge conflict in the changelog, we could put changelog entries in the PR description and move them to the release drafter once the changes are merged instead of updating the changelog file in PRs if we get too many merge conflicts.