Add lnd HTTP proxy to Lightning App

[chill117]

• Needed for [research] Messaging between extension and app running on host #11
• Fork and modify the Lightning App project
• Add an HTTP server that proxies API requests to its lnd child process

See:

• https://github.com/lightninglabs/lightning-app/blob/master/public/electron.js
• https://github.com/lightninglabs/lightning-app/blob/master/public/grpc-client.js