Check integration with Protofire proxy

[LesnyRumcajs]

Summary

A potential alternative to the Lotus Gateway is the Filecoin Subway, used by Protofire. This should work, but let's assert the compatibility first and then we can announce it.

Completion Criteria

• Check the compatibility with the Filecoin Subway
• Write docs in the guide along the lines of https://docs.forest.chainsafe.io/guides/running_with_gateway

Additional Links & Resources

[LesnyRumcajs]

Need to check that filtering (both methods and their params) is in place.

[0xDevNinja]

Hi, I'd like to work on this issue. Could you please assign it to me? Thanks!