[Deliverable] Enable usage with RLN SDK

[chair28980]

Owner: App/Chat Dev

Feature: Rate Limit Manager

FURPS:

• F7. Can consume RLN API to access rate limit and current quota.

Feature: Group Chat

FURPS:

• S3. SDK can be instantiated with a RLN-enabled Waku node.

Checklist:

• Specs: link to specs and/or API definition
• Code: link to GitHub issues/PRs/Epic
• Dogfood: link to dogfooding session/artefact
• Docs: links to README.md or docs.waku.org (TBD)

[fryorcraken]

To review as likely to postpone RLN API work with refocus.