We should add a command line argument --authrpc.jwtsecret=<PATH> that contains the path to the jwt secret. With that, we should validate the jwt token that we receive for requests to the engine api.

To test this, we can uncomment this line: https://github.com/lambdaclass/ethereum-package/pull/1/files#diff-79bf8330a2e72edba847d9ca9de634c4339dc13afb11636b13e0a4775119dcbbR219 and run a localnet with kurtosis.

Acceptance criteria:

• Invalid or missing jwt token should return the appropriate error response
• Valid jwt token should continue with the request.