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.

lcli/src/skip_slots.rs

@@ -102,7 +102,7 @@ pub fn run<E: EthSpec>(
                 })
                 .map_err(|e| format!("Failed to complete task: {:?}", e))?
                 .ok_or_else(|| format!("Unable to locate state at {:?}", state_id))?
-                .data;
+                .into_data();
             let state_root = match state_id {
                 StateId::Root(root) => Some(root),
                 _ => None,