QMK CLI and JSON keymap support (#6176)

* Script to generate keymap.c from JSON file.

* Support for keymap.json

* Add a warning about the keymap.c getting overwritten.

* Fix keymap generating

* Install the python deps

* Flesh out more of the python environment

* Remove defunct json2keymap

* Style everything with yapf

* Polish up python support

* Hide json keymap.c into the .build dir

* Polish up qmk-compile-json

* Make milc work with positional arguments

* Fix a couple small things

* Fix some errors and make the CLI more understandable

* Make the qmk wrapper more robust

* Add basic QMK Doctor

* Clean up docstrings and flesh them out as needed

* remove unused compile_firmware() function

lib/python/qmk/cli/hello.py

@@ -0,0 +1,13 @@
+"""QMK Python Hello World
+
+This is an example QMK CLI script.
+"""
+from milc import cli
+
+
+@cli.argument('-n', '--name', default='World', help='Name to greet.')
+@cli.entrypoint('QMK Hello World.')
+def main(cli):
+    """Log a friendly greeting.
+    """
+    cli.log.info('Hello, %s!', cli.config.general.name)