New feature: Check if a bundle is confirm or not

[chen4903]

I use flashbot to send a bundle to ethereum and get a bundle hash, but I don't know if this bundle confirm or not. It would be good if we could check whether our transaction is contained in the target block or not.

Here is a repo that could be referred: https://github.com/onbjerg/ethers-flashbots/blob/master/src/pending_bundle.rs