feat: Add support of WebSocket transport

[victornguen]

Websocket transport support

Summary

Implemented support of WebSocket transport

Changes

• Add FastApiWebSocketTransport class for WebSocket transport
• Example usage scripts for websocket and multi transport server

Test Updates

• Added mock, real and integration tests for FastApiWebSocketTransport

Checklist before requesting a review

• [X] Added relevant tests
• [X] Run ruff & mypy
• [X] All tests pass