Doc fragments to plugins (#50172)

* promote doc_fragments into actual plugins

  change tests hardcoded path to doc fragments
  avoid sanity in fragments
  avoid improper testing of doc_fragments
  also change runner paths
 fix botmeta
 updated comment for fragments
 updated docs

test/runner/lib/classification.py

@@ -559,7 +559,7 @@ class PathMapper(object):
                     'units': 'all',
                 }
 
-        if path.startswith('lib/ansible/utils/module_docs_fragments/'):
+        if path.startswith('lib/ansible/plugins/docs_fragments/'):
             return {
                 'sanity': 'all',
             }