Reimplement access to backing services as microservice

[gnarea]

Describe the problem

The current implementation, where everything is a library, makes it hard/impossible to distribute migration scripts, as every app would have its own migration system.

Describe the solution you'd like

Most of the code in this library to be moved to a microservice -- basically anything that interacts with the underlying backings services (e.g., Vault). Then this library would become a very thin client to that microservice.

Describe alternatives you've considered

None

Additional context

None