Adding rebase github action for rebasing a current branch

[pacostas]

Summary

This action has been tested here : https://github.com/pacostas/builder-jammy-buildpackless-tiny/actions/runs/23195036484

This PR:

• Adds a new action called rebase-branch. This action rebases the current checked out branch on the main branch. The main branch is passed as an argument with default value main, in case someone would like to use a different base branch (unlikely but there is not harm having it)
• Updates the update-builder-toml.yml github action in order to use this action.

In general I have noticed, that the builders most of the times do not get the latest updates on the builder.toml file, due to the branch despite has been updated, it has not been rebased. The purpose of this PR is to reduce the amount of work that is needed in order to rebase the PRs, wait for the tests to pass, aprove the PR due to a human has rebased it and it can not be merged automatically and then merge them. Also, this will practically end up to not be necessasry almost any human supervision, as in case the PR fails (e.g. network error during the tests of the PR), the rebase will help unblock the PR from this state and will manage to merge it automatically the next time that the update-buidler-toml.yml action will run.

Also, this action can be used across all other github-actions, but I think we can start small with the most important part, that is having the latest changes on the builders, as soon as possible. It will also gives us a better overview whether this action would need some improvement or not in terms of functionality.

Use Cases

Checklist

• I have viewed, signed, and submitted the Contributor License Agreement.
• I have linked issue(s) that this PR should close using keywords or the Github UI (See docs)
• I have added an integration test, if necessary.
• I have reviewed the styleguide for guidance on my code quality.
• I'm happy with the commit history on this PR (I have rebased/squashed as needed).

[dmikusa]

Since you're just running a shell script, you don't have to have this action use a Dockerfile. That is just adding some overhead as it will need to build the container when you want to use this. See https://github.com/pacostas/builder-jammy-buildpackless-tiny/actions/runs/23195036484/job/67401012368

Just an FYI.

[pacostas]

I see, Im just trying to be on the same pattern as the rest of the actions.