ci: assign ~"workflow::ready for development" label to issues without workflow label

What does this MR do?

Adds a new CI script and job to automatically assign workflowready for development to SASTRuleset issues with missing ~workflow::* labels. This tells contractors that the issue is ready to be picked up and worked on.

It also optimizes the pipeline job runs with file change rules so they only run when they are relevant for the changes made.