Make checks.yml reusable

Author: SarahFrench

.github/workflows/checks.yml renamed to .github/workflows/reusable/checks.yml

@@ -15,42 +15,9 @@
 
 name: Quick Checks
 
+# This workflow is reusable and called from multiple, scenario-specific workflows.
 on:
-  # We always run checks on:
-  # - PR merges to main
-  # - PR merges to release branches
-  push:
-    branches:
-      - 'main'
-      - 'v[0-9]+.[0-9]+'
-    tags:
-      - 'v[0-9]+.[0-9]+.[0-9]+*'
-  # We only run checks when pushing to a feature branch:
-  # - If there are changes outside the ignored, non-code paths below
-  push:
-    branches:
-      - '*'
-    branches-ignore:
-      - 'main'
-      - 'v[0-9]+.[0-9]+'
-    paths-ignore:
-      - 'CHANGELOG.md'
-      - '.changes/**'
-      - 'version/VERSION'
-      - 'docs/**'
-  # We only run checks on pull request events:
-  # - If there are changes outside the ignored, non-code paths below
-  pull_request:
-    types:
-      - opened
-      - ready_for_review
-      - reopened
-      - synchronize
-    paths-ignore:
-      - 'CHANGELOG.md'
-      - '.changes/**'
-      - 'version/VERSION'
-      - 'docs/**'
+  workflow_call:
 
 # This workflow runs for not-yet-reviewed external contributions and so it
 # intentionally has no write access and only limited read access to the