Fork aware max values in rpc (#6847)

N/A


  In https://github.com/sigp/lighthouse/pull/6329 we changed `max_blobs_per_block` from a preset to a config value.
We weren't using the right value based on fork in that PR. This is a follow up PR to use the fork dependent values.

In the proces, I also updated other places where we weren't using fork dependent values from the ChainSpec.

Note to reviewer: easier to go through by commit

beacon_node/network/src/sync/tests/lookups.rs

@@ -39,6 +39,7 @@ use lighthouse_network::{
 use slog::info;
 use slot_clock::{SlotClock, TestingSlotClock};
 use tokio::sync::mpsc;
+use types::ForkContext;
 use types::{
     data_column_sidecar::ColumnIndex,
     test_utils::{SeedableRng, TestRandom, XorShiftRng},
@@ -92,6 +93,11 @@ impl TestRig {
             .build();
 
         let chain = harness.chain.clone();
+        let fork_context = Arc::new(ForkContext::new::<E>(
+            Slot::new(0),
+            chain.genesis_validators_root,
+            &chain.spec,
+        ));
 
         let (network_tx, network_rx) = mpsc::unbounded_channel();
         let (sync_tx, sync_rx) = mpsc::unbounded_channel::<SyncMessage<E>>();
@@ -139,6 +145,7 @@ impl TestRig {
                 SamplingConfig::Custom {
                     required_successes: vec![SAMPLING_REQUIRED_SUCCESSES],
                 },
+                fork_context,
                 log.clone(),
             ),
             harness,