fork commetbft to emit tx index finished event through websocket

[beer-1]

Is your feature request related to a problem? Please describe.
In current commetbft, there is no guarantee that the tx indexing is finished when NewBlock event comes out.

Describe the solution you'd like
create new websocket event type TxIndexFinished which is emitted after tx indexing finished.

Describe alternatives you've considered
just pulling the txs and checking the result with /blockchain rpc output.

Additional context