## Issue Addressed
https://github.com/sigp/lighthouse/issues/3091
Extends https://github.com/sigp/lighthouse/pull/3062, adding pre-bellatrix block support on blinded endpoints and allowing the normal proposal flow (local payload construction) on blinded endpoints. This resulted in better fallback logic because the VC will not have to switch endpoints on failure in the BN <> Builder API, the BN can just fallback immediately and without repeating block processing that it shouldn't need to. We can also keep VC fallback from the VC<>BN API's blinded endpoint to full endpoint.
## Proposed Changes
- Pre-bellatrix blocks on blinded endpoints
- Add a new `PayloadCache` to the execution layer
- Better fallback-from-builder logic
## Todos
- [x] Remove VC transition logic
- [x] Add logic to only enable builder flow after Merge transition finalization
- [x] Tests
- [x] Fix metrics
- [x] Rustdocs
Co-authored-by: Mac L <mjladson@pm.me>
Co-authored-by: realbigsean <sean@sigmaprime.io>
## Issue Addressed
N/A
## Proposed Changes
Since Rust 1.62, we can use `#[derive(Default)]` on enums. ✨https://blog.rust-lang.org/2022/06/30/Rust-1.62.0.html#default-enum-variants
There are no changes to functionality in this PR, just replaced the `Default` trait implementation with `#[derive(Default)]`.
## Issue Addressed
Resolves https://github.com/sigp/lighthouse/issues/2763
## Proposed Changes
- Add a workflow which tests that local testnet starts successfully
- Added `set` option into the scripts in order to fail fast so that we can notice errors during starting local testnet.
- Fix errors on MacOS
- The redirect `&>>` is supported since bash v4 but the version bundled in macOS(11.6.1) is v3. a54f119c9b
