Fix todos in deneb code (#4547)

* Low hanging fruits

* Remove unnecessary todo

I think it's fine to not handle this since the calling functions handle the error.
No specific reason imo to handle it in the function as well.

* Rename BlobError to GossipBlobError

I feel this signified better what the error is for. The BlobError was only for failures when gossip
verifying a blob. We cannot get this error when doing rpc validation

* Remove the BlockError::BlobValidation variant

This error was only there to appease gossip verification before publish.
It's unclear how to peer score this error since this cannot actually occur during any
block verification flows.
This commit introuduces an additional error type BlockContentsError to better represent the
Error type

* Add docs for peer scoring (or lack thereof) of AvailabilityCheck errors

* I do not see a non-convoluted way of doing this. Okay to have some redundant code here

* Removing this to catch the failure red handed

* Fix compilation

* Cannot be deleted because some tests assume the trait impl

Also useful to have around for testing in the future imo

* Add some metrics and logs

* Only process `Imported` variant in sync_methods

The only additional thing for other variants that might be useful is logging. We can do that
later if required

* Convert to TryFrom

Not really sure where this would be used, but just did what the comment says.
Could consider just returning the Block variant for a deneb block in the From version

* Unlikely to change now

* This is fine as this is max_rpc_size per rpc chunk (for blobs, it would be 128kb max)

* Log count instead of individual blobs, can delete log later if it becomes too annoying.

* Add block production blob verification timer

* Extend block_straemer test to deneb

* Remove dbg statement

* Fix tests

beacon_node/lighthouse_network/src/rpc/protocol.rs

@@ -134,7 +134,6 @@ pub(crate) const MAX_RPC_SIZE: usize = 1_048_576; // 1M
 /// The maximum bytes that can be sent across the RPC post-merge.
 pub(crate) const MAX_RPC_SIZE_POST_MERGE: usize = 10 * 1_048_576; // 10M
 pub(crate) const MAX_RPC_SIZE_POST_CAPELLA: usize = 10 * 1_048_576; // 10M
-                                                                    // FIXME(sean) should this be increased to account for blobs?
 pub(crate) const MAX_RPC_SIZE_POST_DENEB: usize = 10 * 1_048_576; // 10M
 /// The protocol prefix the RPC protocol id.
 const PROTOCOL_PREFIX: &str = "/eth2/beacon_chain/req";