Add tempest tests for share snapshot metadata

Adds positive and negative tests for share snapshot metadata api.
Works for microversion 2.73 and later.

Partially-implements: bp/metadata-for-share-resources
Depends-On: I91151792d033a4297557cd5f330053d78895eb78
Change-Id: I78cccc6bcd1b8d938b00467d07f3fd6edf7bfc6f
diff --git a/manila_tempest_tests/tests/api/base.py b/manila_tempest_tests/tests/api/base.py
index 34f8e41..42c2fab 100755
--- a/manila_tempest_tests/tests/api/base.py
+++ b/manila_tempest_tests/tests/api/base.py
@@ -562,13 +562,14 @@
     @classmethod
     def create_snapshot_wait_for_active(cls, share_id, name=None,
                                         description=None, force=False,
-                                        client=None, cleanup_in_class=True):
+                                        metadata=None, client=None,
+                                        cleanup_in_class=True):
         if client is None:
             client = cls.shares_v2_client
         if description is None:
             description = "Tempest's snapshot"
         snapshot = client.create_snapshot(
-            share_id, name, description, force)['snapshot']
+            share_id, name, description, force, metadata)['snapshot']
         resource = {
             "type": "snapshot",
             "id": snapshot["id"],