Make all module_utils and plugin_utils private (#887)

* Add leading underscore. Remove deprecated module utils.

* Document module and plugin utils as private. Add changelog fragment.

* Convert relative to absolute imports.

* Remove unnecessary imports.

plugins/module_utils/_cryptography_dep.py

@@ -0,0 +1,81 @@
+# Copyright (c) 2025 Ansible project
+# 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!
+
+"""
+Module utils for cryptography requirements.
+
+Must be kept in sync with plugins/doc_fragments/cryptography_dep.py.
+"""
+
+from __future__ import annotations
+
+import traceback
+import typing as t
+
+from ansible.module_utils.basic import missing_required_lib
+from ansible_collections.community.crypto.plugins.module_utils._version import (
+    LooseVersion,
+)
+
+
+if t.TYPE_CHECKING:
+    from ansible.module_utils.basic import AnsibleModule
+    from ansible_collections.community.crypto.plugins.plugin_utils._action_module import (
+        AnsibleActionModule,
+    )
+    from ansible_collections.community.crypto.plugins.plugin_utils._filter_module import (
+        FilterModuleMock,
+    )
+
+    GeneralAnsibleModule = t.Union[AnsibleModule, AnsibleActionModule, FilterModuleMock]
+
+
+_CRYPTOGRAPHY_IMP_ERR: str | None = None
+_CRYPTOGRAPHY_FILE: str | None = None
+try:
+    import cryptography
+    from cryptography import x509  # noqa: F401, pylint: disable=unused-import
+
+    CRYPTOGRAPHY_VERSION = LooseVersion(cryptography.__version__)
+    _CRYPTOGRAPHY_FILE = cryptography.__file__
+except ImportError:
+    _CRYPTOGRAPHY_IMP_ERR = traceback.format_exc()
+    CRYPTOGRAPHY_FOUND = False
+    CRYPTOGRAPHY_VERSION = LooseVersion("0.0")
+else:
+    CRYPTOGRAPHY_FOUND = True
+
+
+# Corresponds to the community.crypto.cryptography_dep.minimum doc fragment
+COLLECTION_MINIMUM_CRYPTOGRAPHY_VERSION = "3.3"
+
+
+def assert_required_cryptography_version(
+    module: GeneralAnsibleModule,
+    *,
+    minimum_cryptography_version: str = COLLECTION_MINIMUM_CRYPTOGRAPHY_VERSION,
+) -> None:
+    if not CRYPTOGRAPHY_FOUND:
+        module.fail_json(
+            msg=missing_required_lib(f"cryptography >= {minimum_cryptography_version}"),
+            exception=_CRYPTOGRAPHY_IMP_ERR,
+        )
+    if CRYPTOGRAPHY_VERSION < LooseVersion(minimum_cryptography_version):
+        module.fail_json(
+            msg=(
+                f"Cannot detect the required Python library cryptography (>= {minimum_cryptography_version})."
+                f" Only found a too old version ({CRYPTOGRAPHY_VERSION}) at {_CRYPTOGRAPHY_FILE}."
+            ),
+        )
+
+
+__all__ = (
+    "COLLECTION_MINIMUM_CRYPTOGRAPHY_VERSION",
+    "CRYPTOGRAPHY_FOUND",
+    "CRYPTOGRAPHY_VERSION",
+    "assert_required_cryptography_version",
+)