refactor: mark module_utils modules as private (#782)

##### SUMMARY

All `module_utils` are now marked as **private**. None of the modules
were intended for public use.

Similar to
https://togithub.com/ansible-collections/community.general/issues/11312

plugins/module_utils/_storage_box.py

@@ -0,0 +1,69 @@
+# 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
+
+from ._client import client_resource_not_found
+from ._vendor.hcloud.storage_boxes import (
+    BoundStorageBox,
+    StorageBoxesClient,
+)
+
+
+def get(client: StorageBoxesClient, param: str | int) -> BoundStorageBox:
+    """
+    Get a Bound Storage Box either by ID or name.
+
+    If the given parameter is an ID, return a partial Bound Storage Box to reduce the amount
+    of API requests.
+    """
+    try:
+        return BoundStorageBox(
+            client,
+            data={"id": int(param)},
+            complete=False,
+        )
+    except ValueError:  # param is not an id
+        result = client.get_by_name(param)
+        if result is None:
+            # pylint: disable=raise-missing-from
+            raise client_resource_not_found("storage box", param)
+        return result
+
+
+def prepare_result(o: BoundStorageBox):
+    return {
+        "id": o.id,
+        "name": o.name,
+        "storage_box_type": o.storage_box_type.name,
+        "location": o.location.name,
+        "labels": o.labels,
+        "delete_protection": o.protection["delete"],
+        "access_settings": {
+            "reachable_externally": o.access_settings.reachable_externally,
+            "samba_enabled": o.access_settings.samba_enabled,
+            "ssh_enabled": o.access_settings.ssh_enabled,
+            "webdav_enabled": o.access_settings.webdav_enabled,
+            "zfs_enabled": o.access_settings.zfs_enabled,
+        },
+        "username": o.username,
+        "server": o.server,
+        "system": o.system,
+        "status": o.status,
+        "stats": {
+            "size": o.stats.size,
+            "size_data": o.stats.size_data,
+            "size_snapshots": o.stats.size_snapshots,
+        },
+        "snapshot_plan": (
+            None
+            if o.snapshot_plan is None
+            else {
+                "max_snapshots": o.snapshot_plan.max_snapshots,
+                "hour": o.snapshot_plan.hour,
+                "minute": o.snapshot_plan.minute,
+                "day_of_week": o.snapshot_plan.day_of_week,
+                "day_of_month": o.snapshot_plan.day_of_month,
+            }
+        ),
+    }