Trigger CI based on PR labels / modified files

[Theodlz]

On PRs, we run almost all GitHub action workflows, ignoring whether or not they are relevant based on the changes that were made to the codebase.

Ideally, we would like to specify in the workflow yaml files, what labels (or the paths to modified files/directories) are required for the CI to run. This should help minizime the number of concurrent actions that are running, which helps prevent "clogging" when no runners are available which happens when too many workflows are running at once.