Addition of Synchronous Invocation (#127)

* Add core changes for restructue

* Update method to invoke_sync

Author: MOmarMiraj

src/onepassword/core.py

@@ -23,6 +23,10 @@ async def _init_client(client_config):
 async def _invoke(invoke_config):
     return await core.invoke(json.dumps(invoke_config))
 
+# Invoke calls specified business logic from the SDK core.
+def _invoke_sync(invoke_config):
+    return core.invoke_sync(json.dumps(invoke_config))
+
 
 # ReleaseClient releases memory in the SDK core associated with the given client ID.
 def _release_client(client_id):