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/codec/ssz_snappy.rs

@@ -15,11 +15,10 @@ use std::io::{Read, Write};
 use std::marker::PhantomData;
 use std::sync::Arc;
 use tokio_util::codec::{Decoder, Encoder};
-use types::{light_client_bootstrap::LightClientBootstrap, BlobSidecar};
 use types::{
-    EthSpec, ForkContext, ForkName, Hash256, SignedBeaconBlock, SignedBeaconBlockAltair,
-    SignedBeaconBlockBase, SignedBeaconBlockCapella, SignedBeaconBlockDeneb,
-    SignedBeaconBlockMerge,
+    BlobSidecar, EthSpec, ForkContext, ForkName, Hash256, LightClientBootstrap, SignedBeaconBlock,
+    SignedBeaconBlockAltair, SignedBeaconBlockBase, SignedBeaconBlockCapella,
+    SignedBeaconBlockDeneb, SignedBeaconBlockMerge,
 };
 use unsigned_varint::codec::Uvi;