feat: Add kopia_server module

- Manage Kopia repository server users and ACL entries via the
  Kopia CLI.
- Extends community.general._kopia doc fragment for shared password
  and config options.
- Uses fixed args for read-only _get() list_users method.

tests/unit/plugins/modules/test_kopia_server.py

@@ -0,0 +1,11 @@
+# Copyright (c) 2026, Dexter Le <dextersydney2001@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
+
+from __future__ import annotations
+
+from ansible_collections.community.general.plugins.modules import kopia_server
+
+from .uthelper import RunCommandMock, UTHelper
+
+UTHelper.from_module(kopia_server, __name__, mocks=[RunCommandMock])