Proposal: Create tooling to automatically create backports

Problem

Many MRs get merged into GitLab's master branch that are candidates for backporting into past releases.

Examples include:

• A fix to a flaky test
• A fix to a recently introduced bug

This presents a real problem to quality and engineering time when these bugs/flaky tests start affecting past versions.

Proposal

Create a tool to detect merge requests that were merged into the default branch of GitLab based on a set of labels and automatically prepare and merge backports for the versions within the maintenance policy.

Involvement from the MR author would only be required if something goes wrong (the pipeline fails, for example)