CI: add action to tag PRs for release notes

Change Summary

This PR adds the following:

• A custom github action to be able to label the PRs with a label that looks like: rn: <type>[(<scope>)][!]? where <type> and <scope> are understood as per conventional commit specification and ! means Breaking Change. The action assumes one such label only and is able to remove a preexisting label when required. When a label does not exist it can be auto_created if the action is told so via input parameters.
• A workflow that run the action described above when PRs are merged OR when the title is modified post merge. It calls the action with the input parameter to auto create the labels when needed.
• A .github/release.yml file that is used as an instruction manual by Github when generating release notes for a release
• A python script generate_release.py which can be used to generate the previous file given the amount of potential labels that the action can generate based on the supported list of <types> and <scopes>.

The goal behind this is to generate proper release notes based on the PR titles.

Component(s) name

ci

How to test

Need to merge and start seeing the labels.

Checklist

Repository Checklist

• [x] My code has been rebased from devel before I start
• [x] I have read the CONTRIBUTING document.
• [x] My change requires a change to the documentation and documentation have been updated accordingly.
• [x] I have updated molecule CI testing accordingly. (check the box if not applicable)