Wait for txs to be included before returning response in celestia-grpc-client

[damiannolan]

Description

The celestia-grpc-client crate does not wait for txs to be included and thus just returns immediately with a success = true value and a tx hash. This is indicative of how the underlying client is used, since transactions are broadcast asynchronously.
The sync broadcast mode has been removed from cosmos-sdk blockchain for quite a while and therefore the normal approach here is to poll the node using the txHash from the initial request, until a fulfilled response is returned.

The response is currently returned here: https://github.com/celestiaorg/celestia-zkevm/blob/main/crates/celestia-grpc-client/src/client.rs#L120-L126
Note the hardcoded success value and gasUsed.

An option here is to support two approaches:

• client.send_tx() - polls for the fulfilled response when included in a block
• client.send_tx_async() - maintains the current behaviour but adds a flag in the response to indicate async