API for LightClientBootstrap, LightClientFinalityUpdate, LightClientOptimisticUpdate and light client events (#3954)

* rebase and add comment

* conditional test

* test

* optimistic chould be working now

* finality should be working now

* try again

* try again

* clippy fix

* add lc bootstrap beacon api

* add lc optimistic/finality update to events

* fmt

* That error isn't occuring on my computer but I think this should fix it

* Add missing test file

* Update light client types to comply with Altair light client spec.

* Fix test compilation

* Support deserializing light client structures for the Bellatrix fork

* Move `get_light_client_bootstrap` logic to `BeaconChain`. `LightClientBootstrap` API to return `ForkVersionedResponse`.

* Misc fixes.
- log cleanup
- move http_api config mutation to `config::get_config` for consistency
- fix light client API responses

* Add light client bootstrap API test and fix existing ones.

* Fix test for `light-client-server` http api config.

* Appease clippy

* Efficiency improvement when retrieving beacon state.

---------

Co-authored-by: Jimmy Chen <jchen.tc@gmail.com>

beacon_node/lighthouse_network/src/rpc/methods.rs

@@ -17,8 +17,8 @@ use superstruct::superstruct;
 use types::blob_sidecar::BlobIdentifier;
 use types::consts::deneb::MAX_BLOBS_PER_BLOCK;
 use types::{
-    blob_sidecar::BlobSidecar, light_client_bootstrap::LightClientBootstrap, Epoch, EthSpec,
-    Hash256, SignedBeaconBlock, Slot,
+    blob_sidecar::BlobSidecar, Epoch, EthSpec, Hash256, LightClientBootstrap, SignedBeaconBlock,
+    Slot,
 };
 
 /// Maximum number of blocks in a single request.
@@ -571,7 +571,11 @@ impl<T: EthSpec> std::fmt::Display for RPCResponse<T> {
             RPCResponse::Pong(ping) => write!(f, "Pong: {}", ping.data),
             RPCResponse::MetaData(metadata) => write!(f, "Metadata: {}", metadata.seq_number()),
             RPCResponse::LightClientBootstrap(bootstrap) => {
-                write!(f, "LightClientBootstrap Slot: {}", bootstrap.header.slot)
+                write!(
+                    f,
+                    "LightClientBootstrap Slot: {}",
+                    bootstrap.header.beacon.slot
+                )
             }
         }
     }