Migrate 'make git-submodule' to CLI command

Makefile

@@ -430,12 +430,7 @@ lib/%:
 
 .PHONY: git-submodule
 git-submodule:
-	[ -e lib/ugfx ] && rm -rf lib/ugfx || true
-	[ -e lib/pico-sdk ] && rm -rf lib/pico-sdk || true
-	[ -e lib/chibios-contrib/ext/mcux-sdk ] && rm -rf lib/chibios-contrib/ext/mcux-sdk || true
-	[ -e lib/lvgl ] && rm -rf lib/lvgl || true
-	git submodule sync --recursive
-	git submodule update --init --recursive --progress
+	$(QMK_BIN) git-submodule
 
 .PHONY: git-submodules
 git-submodules: git-submodule

builddefs/message.mk

@@ -65,7 +65,7 @@ MSG_CLEANING = Cleaning project:
 MSG_CREATING_LIBRARY = Creating library:
 MSG_GENERATING = Generating:
 MSG_SUBMODULE_DIRTY = $(WARN_COLOR)WARNING:$(NO_COLOR) Some git submodules are out of date or modified.\n\
-Please consider running $(BOLD)make git-submodule$(NO_COLOR).\n\n
+Please consider running $(BOLD)qmk git-submodule$(NO_COLOR).\n\n
 MSG_NO_CMP = $(ERROR_COLOR)Error:$(NO_COLOR)$(BOLD) cmp command not found, please install diffutils\n$(NO_COLOR)
 
 define GENERATE_MSG_MAKE_KB

lib/python/qmk/cli/__init__.py

@@ -61,6 +61,7 @@
     'qmk.cli.generate.rgb_breathe_table',
     'qmk.cli.generate.rules_mk',
     'qmk.cli.generate.version_h',
+    'qmk.cli.git.submodule',
     'qmk.cli.hello',
     'qmk.cli.import.kbfirmware',
     'qmk.cli.import.keyboard',

lib/python/qmk/cli/git/submodule.py

@@ -0,0 +1,22 @@
+import shutil
+from qmk.path import normpath
+
+from milc import cli
+
+REMOVE_DIRS = [
+    'lib/ugfx',
+    'lib/pico-sdk',
+    'lib/chibios-contrib/ext/mcux-sdk',
+    'lib/lvgl',
+]
+
+
+@cli.subcommand('Git Submodule actions.')
+def git_submodule(cli):
+    for folder in REMOVE_DIRS:
+        if normpath(folder).is_dir():
+            print(f"Removing '{folder}'")
+            shutil.rmtree(folder)
+
+    cli.run(['git', 'submodule', 'sync', '--recursive'], capture_output=False)
+    cli.run(['git', 'submodule', 'update', '--init', '--recursive', '--progress'], capture_output=False)