Changes for devnet-8 (#4518)

* Addressed #4487

Add override threshold flag
Added tests for Override Threshold Flag
Override default shown in decimal

* Addressed #4445

Addressed Jimmy's Comments
No need for matches
Fix Mock Execution Engine Tests
Fix clippy
fix fcuv3 bug

* Fix Block Root Calculation post-Deneb

* Addressed #4444

Attestation Verification Post-Deneb
Fix Gossip Attestation Verification Test

* Addressed #4443

Fix Exit Signing for EIP-7044
Fix cross exit test
Move 7044 Logic to signing_context()

* Update EF Tests

* Addressed #4560

* Added Comments around EIP7045

* Combine Altair Deneb to Eliminate Duplicated Code

common/eth2/src/types.rs

@@ -926,7 +926,7 @@ pub struct SseLateHead {
 }
 
 #[superstruct(
-    variants(V1, V2),
+    variants(V1, V2, V3),
     variant_attributes(derive(Clone, Debug, Eq, Hash, PartialEq, Serialize, Deserialize))
 )]
 #[derive(Clone, Debug, Eq, Hash, PartialEq, Deserialize, Serialize)]
@@ -939,8 +939,10 @@ pub struct SsePayloadAttributes {
     pub prev_randao: Hash256,
     #[superstruct(getter(copy))]
     pub suggested_fee_recipient: Address,
-    #[superstruct(only(V2))]
+    #[superstruct(only(V2, V3))]
     pub withdrawals: Vec<Withdrawal>,
+    #[superstruct(only(V3), partial_getter(copy))]
+    pub parent_beacon_block_root: Hash256,
 }
 
 #[derive(PartialEq, Debug, Deserialize, Serialize, Clone)]