Merge devnet 3 (#2859)

## Issue Addressed

N/A

## Proposed Changes

Changes required for the `merge-devnet-3`. Added some more non substantive renames on top of @realbigsean 's commit. 
Note: this doesn't include the proposer boosting changes in kintsugi v3.

This devnet isn't running with the proposer boosting fork choice changes so if we are looking to merge https://github.com/sigp/lighthouse/pull/2822 into `unstable`, then I think we should just maintain this branch for the devnet temporarily. 


Co-authored-by: realbigsean <seananderson33@gmail.com>
Co-authored-by: Paul Hauner <paul@paulhauner.com>

beacon_node/execution_layer/src/engine_api.rs

@@ -83,7 +83,7 @@ pub enum ExecutePayloadResponseStatus {
 pub struct ExecutePayloadResponse {
     pub status: ExecutePayloadResponseStatus,
     pub latest_valid_hash: Option<Hash256>,
-    pub message: Option<String>,
+    pub validation_error: Option<String>,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Serialize)]
@@ -107,7 +107,7 @@ pub struct ExecutionBlock {
 pub struct PayloadAttributes {
     pub timestamp: u64,
     pub random: Hash256,
-    pub fee_recipient: Address,
+    pub suggested_fee_recipient: Address,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq)]