pw_presubmit: Update code format step names

This changes the names of the code format steps to lowercase with
underscores to make them consistent with all other steps and easy to
specify via the --step CLI option.

Change-Id: Ie319f36da77fdb0218337ea418ed6e938b6ba317
diff --git a/pw_presubmit/py/pw_presubmit/format_code.py b/pw_presubmit/py/pw_presubmit/format_code.py
index a489fa1..0aef790 100755
--- a/pw_presubmit/py/pw_presubmit/format_code.py
+++ b/pw_presubmit/py/pw_presubmit/format_code.py
@@ -254,7 +254,8 @@
         if errors:
             raise pw_presubmit.PresubmitFailure
 
-    check_code_format.__name__ = f'{code_format.language} format'
+    language = code_format.language.lower().replace('+', 'p').replace(' ', '_')
+    check_code_format.__name__ = f'{language}_format'
 
     return check_code_format