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/_pkg_req.py

@@ -0,0 +1,80 @@
+# Copyright (c) 2025, Alexei Znamensky <russoz@gmail.com>
+# 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
+
+# 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
+
+from ansible_collections.community.general.plugins.module_utils import _deps as deps
+
+if t.TYPE_CHECKING:
+    from ansible.module_utils.basic import AnsibleModule
+
+
+with deps.declare("packaging"):
+    from packaging.requirements import Requirement
+    from packaging.version import InvalidVersion
+    from packaging.version import parse as parse_version
+
+
+class PackageRequirement:
+    def __init__(self, module: AnsibleModule, name: str) -> None:
+        self.module = module
+        self.parsed_name, self.requirement = self._parse_spec(name)
+
+    def _parse_spec(self, name: str) -> tuple[str, Requirement | None]:
+        """
+        Parse a package name that may include version specifiers using PEP 508.
+        Returns a tuple of (name, requirement) where requirement is of type packaging.requirements.Requirement and it may be None.
+
+        Example inputs:
+            "package"
+            "package>=1.0"
+            "package>=1.0,<2.0"
+            "package[extra]>=1.0"
+            "package[foo,bar]>=1.0,!=1.5"
+
+        :param name: Package name with optional version specifiers and extras
+        :return: Tuple of (name, requirement)
+        :raises ValueError: If the package specification is invalid
+        """
+        if not name:
+            return name, None
+
+        # Quick check for simple package names
+        if not any(c in name for c in ">=<!~[]"):
+            return name.strip(), None
+
+        deps.validate(self.module, "packaging")
+
+        try:
+            req = Requirement(name)
+            return req.name, req
+
+        except Exception as e:
+            raise ValueError(f"Invalid package specification for '{name}': {e}") from e
+
+    def matches_version(self, version: str):
+        """
+        Check if a version string fulfills a version specifier.
+
+        :param version: Version string to check
+        :return: True if version fulfills the requirement, False otherwise
+        :raises ValueError: If version is invalid
+        """
+        # If no spec provided, any version is valid
+        if not self.requirement:
+            return True
+
+        try:
+            # Parse version string
+            ver = parse_version(version)
+
+            return ver in self.requirement.specifier
+
+        except InvalidVersion as e:
+            raise ValueError(f"Invalid version '{version}': {e}") from e