For blockchains that have an execution and consensus layer client, automate JWT creation

[chriswessels]

For blockchains like Ethereum, that typically have two clients and a JWT for authentication purposes, we currently require that either a literal value is passed, or an existing secret. For consensus layer charts, we could have an option where the JWT is generated and created as a secret, so that only the secret name must be passed in the dependent (execution layer) chart values.