Add support for websocket subscriptions to txid
Note: changes to `chronik.ts` from running the script `npm run build-proto`
This is a tricky one to test. Would be nice to have just one new file for testing txid ws subscriptions. However, I'm not able to figure out how to make the txids deterministic in tests that finalize blocks with avalanche. We want to show that we can subscribe to a txid before it is broadcast and see it through its various lifecycle stages.
To do this, we
- Show we can get a tx finalized notification in `websockets.ts`
- Show we can get added and removed from mempool notifications in `ws_txid.ts`