Add RPC benchmark results

This MR aims to persist the results of the RPC benchmark tool. In addition to that, it notifies, in the doc, the existence of the framework

Manually testing the MR

Look at the generated doc (brows the pipeline doc artifacts and look for _build/index.html)

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR