Add file state (#316)

* Add file state

Change-Id: I0fd786bab6f14184a6034bc086a82ac827adbc11

* Update google/generativeai/types/file_types.py

Author: MarkDaoust

google/generativeai/types/file_types.py

@@ -66,6 +66,10 @@ def sha256_hash(self) -> bytes:
     def uri(self) -> str:
         return self._proto.uri
 
+    @property
+    def state(self) -> glm.File.State:
+        return self._proto.state
+
     def delete(self):
         client = get_default_file_client()
         client.delete_file(name=self.name)