CI: Add workflow for codebase formatting (#7382)

* Add workflow for codebase formatting

* stash

* review comments

* Swap to a more complete push action

lib/python/qmk/cli/fileformat.py

@@ -0,0 +1,13 @@
+"""Format files according to QMK's style.
+"""
+from milc import cli
+
+import subprocess
+
+
+@cli.subcommand("Format files according to QMK's style.", hidden=True)
+def fileformat(cli):
+    """Run several general formatting commands.
+    """
+    dos2unix = subprocess.run(['bash', '-c', 'dos2unix **'])
+    return dos2unix.returncode