Add blob_sidecar event to SSE (#4790)

* Add `blob_sidecar` event to SSE.

* Return 202 if a block is published but failed blob validation when validation level is `Gossip`.

* Move `BlobSidecar` event to `process_gossip_blob` and add test.

* Emit `BlobSidecar` event when blobs are received over rpc.

* Improve test assertions on `SseBlobSidecar`s.

* Add quotes to blob index serialization in `SseBlobSidecar`

Co-authored-by: realbigsean <seananderson33@GMAIL.com>

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Co-authored-by: realbigsean <seananderson33@GMAIL.com>

beacon_node/beacon_chain/tests/main.rs

@@ -2,6 +2,7 @@ mod attestation_production;
 mod attestation_verification;
 mod block_verification;
 mod capella;
+mod events;
 mod merge;
 mod op_verification;
 mod payload_invalidation;