We need copies of test_awacs_field_schema.proto and test_awacs_message_schema.proto for tests.
Because of the way protobuf generated files deal with imports.

They are not copies exactly. Protobuf has singleton registry of messages and
if we have several copies of messages in different files, which are imported in application,
we'll get something like this:
``
Extensions "test_awacs_field_schema.minimum" and "test_awacs_field_schema.minimum" both try to extend message type "google.protobuf.FieldOptions" with field number 50001.
``
To avoid that we shift extension numbers in copied message definitions.