Implement PeerDAS sync (#15564)

* PeerDAS: Implement sync

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Satyajit's comment.

* Partially fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Add tests for `sendDataColumnSidecarsRequest`.

* Fix Satyajit's comment.

* Implement `TestSendDataColumnSidecarsRequest`.

* Implement `TestFetchDataColumnSidecarsFromPeers`.

* Implement `TestUpdateResults`.

* Implement `TestSelectPeers`.

* Implement `TestCategorizeIndices`.

* Fix James' comment.

* Fix James's comment.

* Fix James' commit.

* Fix James' comment.

* Fix James' comment.

* Fix flakiness in `TestSelectPeers`.

* Update cmd/beacon-chain/flags/config.go

Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>

* Fix Preston's comment.

* Fix James's comment.

* Implement `TestFetchDataColumnSidecars`.

* Revert "Fix Potuz's comment."

This reverts commit c45230b455.

* Fix Potuz's comment.

* Revert "Fix James' comment."

This reverts commit a3f919205a.

* Fix James' comment.

* Fix Preston's comment.

* Fix James' comment.

* `selectPeers`: Avoid map with key but empty value.

* Fix typo.

* Fix Potuz's comment.

* Fix Potuz's comment.

* Fix James' comment.

* Add DataColumnStorage and SubscribeAllDataSubnets flag.

* Add extra flags

* Fix Potuz's and Preston's comment.

* Add rate limiter check.

---------

Co-authored-by: Preston Van Loon <pvanloon@offchainlabs.com>
Co-authored-by: Kasey Kirkham <kasey@users.noreply.github.com>

beacon-chain/db/filesystem/data_column.go

@@ -100,6 +100,14 @@ type (
 	}
 )
 
+// DataColumnStorageReader is an interface to read data column sidecars from the filesystem.
+type DataColumnStorageReader interface {
+	Summary(root [fieldparams.RootLength]byte) DataColumnStorageSummary
+	Get(root [fieldparams.RootLength]byte, indices []uint64) ([]blocks.VerifiedRODataColumn, error)
+}
+
+var _ DataColumnStorageReader = &DataColumnStorage{}
+
 // WithDataColumnBasePath is a required option that sets the base path of data column storage.
 func WithDataColumnBasePath(base string) DataColumnStorageOption {
 	return func(b *DataColumnStorage) error {