AutoRelease + Header Checker Upgrades (#482)

* Initial version where all deps are pylibs
* mechanism for undoing an autorelease
* misc refactor touchups
* +mechanism to baseline older commit into detached HEAD tag
* decouple kernel check configs + misc refactor improvements
* improved compatibility with git action
* Get pushes working in git action with release
* Fix header-check issue when same deletion occurs in parallel
* Add help message in case check fails
* Address PR feedback

.github/workflows/core-checks.yml

@@ -0,0 +1,46 @@
+name: Core-Checker
+
+on: [pull_request]          
+
+jobs:
+  core-checker:
+    name: FreeRTOS Core Checks
+    runs-on: ubuntu-latest
+    steps:
+      # Install python 3
+      - name: Tool Setup
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.8.5
+          architecture:   x64  
+        env:  
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} 
+      
+      # Use the checks as defined by the user, so they can locally adjust as needed
+      - name: Checkout FreeRTOS Tools
+        uses: actions/checkout@v2
+        with:
+          ref:  ${{ github.event.pull_request.head.sha }}
+          path: tools
+
+      # Checkout user pull request changes
+      - name: Checkout Pull Request
+        uses: actions/checkout@v2
+        with:
+          ref:  ${{ github.event.pull_request.head.sha }}
+          path: inspect  
+          
+      # Collect all affected files
+      - name: Collecting changed files
+        uses: lots0logs/gh-action-get-changed-files@2.1.4
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+      
+      # Run checks     
+      - name: Check File Headers
+        run: |
+          cd inspect
+          export PYTHONPATH=tools/.github/scripts:${PYTHONPATH}
+          .github/scripts/core_checker.py --json ${HOME}/files_modified.json ${HOME}/files_added.json ${HOME}/files_renamed.json
+          exit $?
+