Create a github action that prevents a PR from being merged if label is applied

[trillium]

Overview

Create a GitHut Action to prevent merging when the waiting to merge label is applied

Context

Sometimes we've got a PR that is breaking until other aspects are handled (eg #1502), and we need a way to accept these PRs but hold off on allowing them to be merged. This can be handled with a GitHub Action.

Action Items

• Add a github action that prevents a PR from being merged if the waiting to merge label is applied