Distribute block data in compact blocks as block parts

[evan-forbes]

Its possible to add metadata to the compact block that allows for txs that are included in the mempool to be converted into block parts. This would allow for distributing block data quicker since distributing smaller messages is significantly quicker than distributing larger chunks of data.

Alternatively, we could also try to come up with a scheme that allows the distribution of all txs in the mempool using block parts. Presumably, this would just involve gossiping and checking the PFB portion of the BlobTx first, and then proceeding to gossip the rest of the "blob parts" if that PFB is valid.