Poll the engine_exchangeTransitionConfigurationV1 endpoint (#3047)

## Issue Addressed

There has been an [`engine_exchangetransitionconfigurationv1`](https://github.com/ethereum/execution-apis/blob/main/src/engine/specification.md#engine_exchangetransitionconfigurationv1) method added to the execution API specs.

The `engine_exchangetransitionconfigurationv1` will be polled every 60s as per this PR: https://github.com/ethereum/execution-apis/pull/189. If that PR is merged as-is, then we will be matching the spec. If that PR *is not* merged, we are still fully compatible with the spec, but just doing more than we are required.

## Additional Info

- [x] ~~Blocked on #2837~~
- [x] Add method to EE integration tests

beacon_node/execution_layer/src/engine_api/json_structures.rs

@@ -363,6 +363,15 @@ impl From<ForkchoiceUpdatedResponse> for JsonForkchoiceUpdatedV1Response {
     }
 }
 
+#[derive(Clone, Copy, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct TransitionConfigurationV1 {
+    pub terminal_total_difficulty: Uint256,
+    pub terminal_block_hash: ExecutionBlockHash,
+    #[serde(with = "eth2_serde_utils::u64_hex_be")]
+    pub terminal_block_number: u64,
+}
+
 /// Serializes the `logs_bloom` field of an `ExecutionPayload`.
 pub mod serde_logs_bloom {
     use super::*;