Allow Request Invoicing to use Hasura as an alternative to accessing Subgraphs directly

[MantisClone]

Motivation

• Simplify env vars to one Hasura URL instead of 20 Subgraph URLs
• Possibly reduce subgraph usage if Hasura Enterprise supports caching (See Issue https://github.com/RequestNetwork/private-issues/issues/125)

[MantisClone]

Copy from Request Scan