## Issue Addressed
N/A
## Proposed Changes
Make simulator merge compatible. Adds a `--post_merge` flag to the eth1 simulator that enables a ttd and simulates the merge transition. Uses the `MockServer` in the execution layer test utils to simulate a dummy execution node.
Adds the merge transition simulation to CI.
## Issue Addressed
Resolves#3015
## Proposed Changes
Add JWT token based authentication to engine api requests. The jwt secret key is read from the provided file and is used to sign tokens that are used for authenticated communication with the EL node.
- [x] Interop with geth (synced `merge-devnet-4` with the `merge-kiln-v2` branch on geth)
- [x] Interop with other EL clients (nethermind on `merge-devnet-4`)
- [x] ~Implement `zeroize` for jwt secrets~
- [x] Add auth server tests with `mock_execution_layer`
- [x] Get auth working with the `execution_engine_integration` tests
Co-authored-by: Paul Hauner <paul@paulhauner.com>
