Add DataColumnSidecar gossip topic and message handling (#6147)

* Add `DataColumnSidecar` gossip topic and verification (#5050 and #5783).

* Remove gossip verification changes (#5783).

* Merge branch 'unstable' into data-column-gossip

# Conflicts:
#	beacon_node/beacon_chain/src/data_column_verification.rs
#	beacon_node/beacon_chain/src/lib.rs

* Add gossip cache timeout for data columns. Rename data column metrics for consistency.

* Remove usage of `unimplemented!` and address review comments.

* Remove unnused `GossipDataColumnError` variants and address review comments.

* Merge branch 'unstable' into data-column-gossip

* Update Cargo.lock

* Arc `ChainSpec` in discovery to avoid performance regression when needing to clone it repeatedly.

beacon_node/beacon_chain/src/data_availability_checker.rs

@@ -20,6 +20,7 @@ mod error;
 mod overflow_lru_cache;
 mod state_lru_cache;
 
+use crate::data_column_verification::GossipVerifiedDataColumn;
 pub use error::{Error as AvailabilityCheckError, ErrorCategory as AvailabilityCheckErrorCategory};
 use types::non_zero_usize::new_non_zero_usize;
 
@@ -188,6 +189,14 @@ impl<T: BeaconChainTypes> DataAvailabilityChecker<T> {
         )
     }
 
+    pub fn put_gossip_data_columns(
+        &self,
+        _gossip_data_columns: Vec<GossipVerifiedDataColumn<T>>,
+    ) -> Result<Availability<T::EthSpec>, AvailabilityCheckError> {
+        // TODO(das) to be implemented
+        Err(AvailabilityCheckError::Unexpected)
+    }
+
     /// Check if we have all the blobs for a block. Returns `Availability` which has information
     /// about whether all components have been received or more are required.
     pub fn put_pending_executed_block(