Improve error types for envelopes (#9414)

N/A


  Currently, we have `EnvelopeError` having a `ImportError` wrapping a `BlockError`. I feel this is extremely unintuitive because most of the envelope processing functions can simply return an `EnvelopeError` that makes sense in the function's context. It revealed further ugliness when implementing range sync in #9362

This PR does 2 main things:
1. Removes `ImportError(BlockError)` variant
2. Adds `EnvelopeError(EnvelopeError)` variant to a `BlockError`.

I feel this is more natural as there can be envelope errors when we try importing a Block but envelope errors can be contained to just envelope related errors.

The main blocker to doing this was `PayloadVerificationHandle` returning a `BlockError`. It uses a very small subset of `BlockError` which I extracted to its own error type which can be converted into both a BlockError and EnvelopeError.

This allows us to keep most of the pure envelope processing functions to just return EnvelopeErrors while we convert it to a `BlockError` only in import paths where we need to return a consolidated `BlockError`.


Co-Authored-By: Pawan Dhananjay <pawandhananjay@gmail.com>

beacon_node/beacon_chain/src/execution_payload.rs

@@ -9,7 +9,7 @@
 
 use crate::{
     BeaconChain, BeaconChainError, BeaconChainTypes, BlockError, BlockProductionError,
-    ExecutionPayloadError,
+    ExecutionPayloadError, PayloadVerificationError,
 };
 use execution_layer::{
     BlockProposalContentsType, BuilderParams, NewPayloadRequest, PayloadAttributes,
@@ -104,7 +104,9 @@ impl<T: BeaconChainTypes> PayloadNotifier<T> {
         })
     }
 
-    pub async fn notify_new_payload(self) -> Result<PayloadVerificationStatus, BlockError> {
+    pub async fn notify_new_payload(
+        self,
+    ) -> Result<PayloadVerificationStatus, PayloadVerificationError> {
         if let Some(precomputed_status) = self.payload_verification_status {
             Ok(precomputed_status)
         } else {
@@ -133,7 +135,7 @@ pub async fn notify_new_payload<T: BeaconChainTypes>(
     slot: Slot,
     parent_beacon_block_root: Hash256,
     new_payload_request: NewPayloadRequest<'_, T::EthSpec>,
-) -> Result<PayloadVerificationStatus, BlockError> {
+) -> Result<PayloadVerificationStatus, PayloadVerificationError> {
     let execution_layer = chain
         .execution_layer
         .as_ref()