Ability to run jobs depending on what files are changed

Hello,

I would like to request a feature which would allow us to run certain jobs based on what files have been changed. This would allow people to use a monorepo approach to version control for related applications and not waste CI resources testing every application if only a single application is changed.

Example config which would be ideal: https://gist.github.com/klj613/f4f8a2e72b59af504939f17fbaf5b441

I know I can achieve this via shell scripts however would be nice if this was a first class citizen so the build time isn’t “1 second” for skipped jobs.

This is a duplicate of How to skip jobs based on the files changed in a subdirectory?.