Guardian integration with automatic payment provisioning with HIP-991

### Problem description
Guardian ecosystem can include 'pay as you go' data and/or service providers, Guardian support for standardized payment rails would help to reduce integration complexity and ease adoption. HIP-991 may be a suitable mechanism for this.

### Requirements
Investigate the feasibility of using HIP-991 as a payment integration mechanism for Guardian users to pay for Demia storage

### Definition of done
TBD

### Acceptance criteria
Guardian should support 'paid for' services (e.g.Demia as a storage solution) such that they service can be purchased via the mechanism developed by this ticket.