Handle inserting disconnected blocks gracefully

[mattsse]

We may receive a (partially) disconnected block as new payload or when we download it.

this block can't be executed and would currently result in a BlockHashNotFound error if we don't have the last block in that chain:

reth/crates/engine/tree/src/tree/mod.rs

Line 859 in d7db001

let historical = self.provider.state_by_block_hash(parent_hash)?;

TODO

• handle this case gracefully and buffer the block if it's a new payload