The relay-kit needs to use the BasePack structure

[dasanra]

Description

The relay-kit it's still not using the same package structure as the auth-kit or the onramp-kit. This will make more difficult in the future to add other relay providers. The current relay-kit implementation is stable enough to add the same pattern to the kit, ensuring code consistency across all the kits.

Additional context

Check the auth-kit and onramp-kit folder structure, using a BasePack file that defines the minimum interface