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.

tests/unit/plugins/module_utils/test__opennebula.py

@@ -0,0 +1,75 @@
+# Copyright (c) 2023, Michal Opala <mopala@opennebula.io>
+# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+from __future__ import annotations
+
+import textwrap
+
+import pytest
+
+from ansible_collections.community.general.plugins.module_utils._opennebula import flatten, render
+
+FLATTEN_VALID = [
+    ([[[1]], [2], 3], False, [1, 2, 3]),
+    ([[[1]], [2], 3], True, [1, 2, 3]),
+    ([[1]], False, [1]),
+    ([[1]], True, 1),
+    (1, False, [1]),
+    (1, True, 1),
+]
+
+RENDER_VALID = [
+    (
+        {
+            "NIC": {"NAME": "NIC0", "NETWORK_ID": 0},
+            "CPU": 1,
+            "MEMORY": 1024,
+        },
+        textwrap.dedent("""
+            CPU="1"
+            MEMORY="1024"
+            NIC=[NAME="NIC0",NETWORK_ID="0"]
+        """).strip(),
+    ),
+    (
+        {
+            "NIC": [
+                {"NAME": "NIC0", "NETWORK_ID": 0},
+                {"NAME": "NIC1", "NETWORK_ID": 1},
+            ],
+            "CPU": 1,
+            "MEMORY": 1024,
+        },
+        textwrap.dedent("""
+            CPU="1"
+            MEMORY="1024"
+            NIC=[NAME="NIC0",NETWORK_ID="0"]
+            NIC=[NAME="NIC1",NETWORK_ID="1"]
+        """).strip(),
+    ),
+    (
+        {
+            "EMPTY_VALUE": None,
+            "SCHED_REQUIREMENTS": 'CLUSTER_ID="100"',
+            "BACKSLASH_ESCAPED": "this is escaped: \\n; this isn't: \"\nend",
+        },
+        textwrap.dedent("""
+            BACKSLASH_ESCAPED="this is escaped: \\\\n; this isn't: \\"
+            end"
+            SCHED_REQUIREMENTS="CLUSTER_ID=\\"100\\""
+        """).strip(),
+    ),
+]
+
+
+@pytest.mark.parametrize("to_flatten,extract,expected_result", FLATTEN_VALID)
+def test_flatten(to_flatten, extract, expected_result):
+    result = flatten(to_flatten, extract)
+    assert result == expected_result, repr(result)
+
+
+@pytest.mark.parametrize("to_render,expected_result", RENDER_VALID)
+def test_render(to_render, expected_result):
+    result = render(to_render)
+    assert result == expected_result, repr(result)