## Issue Addressed Part of https://github.com/sigp/lighthouse/issues/3118, continuation of https://github.com/sigp/lighthouse/pull/3257 and https://github.com/sigp/lighthouse/pull/3283 ## Proposed Changes - Merge the [`Engines`](https://github.com/sigp/lighthouse/blob/9c429d0764ed91cf56efb8a47a35a556b54a86a4/beacon_node/execution_layer/src/engines.rs#L161-L165) struct and [`Engine` ](https://github.com/sigp/lighthouse/blob/9c429d0764ed91cf56efb8a47a35a556b54a86a4/beacon_node/execution_layer/src/engines.rs#L62-L67) - Remove unnecessary generics ## Additional Info There is more cleanup to do that will come in subsequent PRs