[WEBSITE] Add a gRPC server the the developer infrastructure for BCHA

Summary: As per title, links to https://grpc.fabien.cash

Test Plan:

make serve

Reviewers: #bitcoin_abc, josephroyking

Reviewed By: #bitcoin_abc, josephroyking

Subscribers: josephroyking

Differential Revision: https://reviews.bitcoinabc.org/D8551