Third-Part/Other addition: RSocket (#7054)

Third-Part/Other addition: RSocket

Supports aiohttp as a transport layer.

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: jell-o-fishi

docs/third_party.rst

@@ -292,3 +292,6 @@ ask to raise the status.
 
 - `aiohttp-catcher <https://github.com/yuvalherziger/aiohttp-catcher>`_
   An aiohttp middleware library for centralized error handling in aiohttp servers.
+
+- `rsocket <https://github.com/rsocket/rsocket-py>`_
+  Python implementation of `RSocket protocol <https://rsocket.io>`_.