[Feature Request]: Accepting user's JWT secret

### Implementation ideas

During initialisation/restart phase, we should have a possibility for end users to inject their secret through the node cli/rpc-endpoint.

Ideally, during the initialisation phase, we can let setting up whatever secret with no restrictions whatsoever - can be a simple CLI flag

If during runtime, the user wants to rotate secrets - we should have a dedicated endpoint to do so and ask for the previous token as usual admin perms