Add UniqueIdentifier filtering support for the Locate operation

This change updates Locate operation support in the PyKMIP server,
allowing users to filter objects based on the object's Unique
Identifier. Unit tests and integration tests have been added to
test and verify the correctness of this feature.

Additionally, the Locate demo scripts have also been updated to
support Unique Identifier filtering. Simply use the
"--unique-identifier" flag to specify a Unique Identifier string
value for the Locate script to filter on.

kmip/demos/utils.py

@@ -287,6 +287,15 @@ def build_cli_parser(operation=None):
             dest="cryptographic_length",
             help="The cryptographic length of the secret (e.g., 128, 2048)"
         )
+        parser.add_option(
+            "-i",
+            "--unique-identifier",
+            action="store",
+            type="str",
+            default=None,
+            dest="unique_identifier",
+            help="The unique identifier of the secret (e.g., 1, 2, 3)"
+        )
     elif operation is Operation.REGISTER:
         parser.add_option(
             "-f",