CmdRunner module utils: deprecate format method `as_default_type()` (#6601)

* CmdRunner module utils: deprecate format method `as_default_type()`

* add changelog frag

changelogs/fragments/6601-cmdrunner-deprecate-default-type.yml

@@ -0,0 +1,2 @@
+deprecated_features:
+  - CmdRunner module utils - deprecate ``cmd_runner_fmt.as_default_type()`` formatter (https://github.com/ansible-collections/community.general/pull/6601).

plugins/module_utils/cmd_runner.py

@@ -147,6 +147,11 @@ class _Format(object):
 
     @staticmethod
     def as_default_type(_type, arg="", ignore_none=None):
+        #
+        # DEPRECATION: This method is deprecated and will be removed in community.general 10.0.0
+        #
+        # Instead of using the implicit formats provided here, use the explicit necessary format method.
+        #
         fmt = _Format
         if _type == "dict":
             return fmt.as_func(lambda d: ["--{0}={1}".format(*a) for a in iteritems(d)], ignore_none=ignore_none)