Allow to limit by which PRs are triggered by either PR number(s) or branch format

[roryp2]

I want to be able to create a pipeline for a specific PR while still getting the git hooks that this resource provides, but currently that isn't possible without also providing a git reference for that PR which is too limiting (via the version).

Either limiting by a pr number or based on a branch name or branch regex would be useful.

I've created a fork to test by filtering by a specific PR number which does exactly what I need, happy for more feedback on it: master...roryp2:master

[crstamps2]

Why not just create a pipeline for the branch in question, ignoring the PR aspect of it all together?

[roryp2]

This is still useful for the PR hooks, but I guess it would be easier just to use the git resource and create a separate PR hook resource