QA: investigate opportunity to have exposed API to test waku2 methods

[anastasiyaig]

1. waku methods are RPC methods we can call now from Node Management tab
2. we want to know the list of the methods supported
3. we want to test them avoiding UI (call the RPC directly)

[anastasiyaig]

this is being reflected in status-im/status-go#4595 and i will also build some doc we drafted with Aaron later on