Support cancellation ability in the `BlindedBlockRelayer` trait

[ralexstokes]

https://github.com/ralexstokes/mev-rs/blob/9d88a2386b58c2948fa850f0dd4b3dfe18bd4962/mev-rs/src/blinded_block_relayer/mod.rs#L18-L21

submit_bid should support some way for the caller to signal they want to enable cancellations

going by the current API, it looks like can get away with just adding a bool param to this trait method