ContextDeserialize and Beacon API Improvements (#7372)

* #7286
* BeaconAPI is not returning a versioned response when it should for some V1 endpoints
* these [strange functions with vX in the name that still accept `endpoint_version` arguments](https://github.com/sigp/lighthouse/blob/stable/beacon_node/http_api/src/produce_block.rs#L192)

This refactor is a prerequisite to get the fulu EF tests running.

beacon_node/tests/test.rs

@@ -41,7 +41,7 @@ fn http_server_genesis_state() {
         .block_on(remote_node.get_debug_beacon_states(StateId::Slot(Slot::new(0))))
         .expect("should fetch state from http api")
         .unwrap()
-        .data;
+        .into_data();
 
     let mut db_state = node
         .client