fix(rust): echo service initialization

[adrianbenavides]

After the recent command optimization changes, we stopped creating a separated ockam context when creating a foreground node with configuration.

We've been avoiding that on purpose because we had a known bug that was causing the echo service to stop working correctly if the ockam context was shared.

Turns out that we were recreating the echo service after being set as a consumer for the secure channel listener:

• start_echoer_service deletes the echoer service and recreates it, so this must be called first; otherwise, we lose the flow controls
• initialize_default_services/create_secure_channel_listener adds the echoer as a consumer