Make all doc fragments, module utils, and plugin utils private (#11896)

* Make all doc fragments private.

* Make all plugin utils private.

* Make all module utils private.

* Reformat.

* Changelog fragment.

* Update configs and ignores.

* Adjust unit test names.

plugins/module_utils/_mh/exceptions.py

@@ -0,0 +1,24 @@
+# (c) 2020, Alexei Znamensky <russoz@gmail.com>
+# Copyright (c) 2020, Ansible Project
+# Simplified BSD License (see LICENSES/BSD-2-Clause.txt or https://opensource.org/licenses/BSD-2-Clause)
+# SPDX-License-Identifier: BSD-2-Clause
+
+# Note that this module util is **PRIVATE** to the collection. It can have breaking changes at any time.
+# Do not use this from other collections or standalone plugins/modules!
+
+from __future__ import annotations
+
+import typing as t
+
+
+class ModuleHelperException(Exception):
+    def __init__(self, msg: str, update_output: dict[str, t.Any] | None = None, *args, **kwargs) -> None:
+        self.msg: str = msg or f"Module failed with exception: {self}"
+        if update_output is None:
+            update_output = {}
+        self.update_output: dict[str, t.Any] = update_output
+        super().__init__(*args)
+
+
+class _UnhandledSentinel(Exception):
+    pass