CI: Add workflow for codebase formatting (#7382)

* Add workflow for codebase formatting

* stash

* review comments

* Swap to a more complete push action

.github/workflows/format.yaml

@@ -0,0 +1,34 @@
+name: Format Codebase
+
+on:
+  push:
+    branches:
+    - master
+
+jobs:
+  generate:
+    runs-on: ubuntu-latest
+    container: qmkfm/base_container
+
+    # protect against those who develop with their fork on master
+    if: github.repository == 'qmk/qmk_firmware'
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Install dependencies
+      run: |
+        apt-get update && apt-get install -y dos2unix
+
+    - name: Format files
+      run: |
+        bin/qmk cformat
+        bin/qmk pyformat
+        bin/qmk fileformat
+
+    - name: Commit files
+      uses: stefanzweifel/git-auto-commit-action@v4
+      with:
+        commit_message: "Format code according to conventions for ${GITHUB_SHA}"
+        commit_user_name: QMK Bot
+        commit_user_email: hello@qmk.fm