Implement proposer duties v2 endpoint (#8918)

Fix the issue with the `proposer_duties` endpoint using the wrong dependent root post-Fulu by implementing the new v2 endpoint:

- https://github.com/ethereum/beacon-APIs/pull/563

We need to add this in time for Gloas, and then we can we can deprecate and remove v1.


  - Add a new API handler for the v2 endpoint
- Add client code in the `eth2` crate
- Update existing tests and add some new ones to confirm the different behaviour of v1 and v2

There's a bit of test duplication with v1, but this will be resolved once v1 and its tests are deleted.


Co-Authored-By: Michael Sproul <michael@sigmaprime.io>

Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>

Co-Authored-By: chonghe <44791194+chong-he@users.noreply.github.com>

beacon_node/http_api/src/lib.rs

@@ -263,6 +263,7 @@ pub fn prometheus_metrics() -> warp::filters::log::Log<impl Fn(warp::filters::lo
                 .or_else(|| starts_with("v1/validator/contribution_and_proofs"))
                 .or_else(|| starts_with("v1/validator/duties/attester"))
                 .or_else(|| starts_with("v1/validator/duties/proposer"))
+                .or_else(|| starts_with("v2/validator/duties/proposer"))
                 .or_else(|| starts_with("v1/validator/duties/sync"))
                 .or_else(|| starts_with("v1/validator/liveness"))
                 .or_else(|| starts_with("v1/validator/prepare_beacon_proposer"))
@@ -2464,7 +2465,7 @@ pub fn serve<T: BeaconChainTypes>(
 
     // GET validator/duties/proposer/{epoch}
     let get_validator_duties_proposer = get_validator_duties_proposer(
-        eth_v1.clone(),
+        any_version.clone(),
         chain_filter.clone(),
         not_while_syncing_filter.clone(),
         task_spawner_filter.clone(),