Integrate Redis and NGINX proxy/load balancer for backend services

[williamtnguyen]

This change integrates Redis into the session server backend, which allows us to horizontally scale that service, all the state will be stored in Redis, so the state is no longer tied to one machine.

It also integrates NGINX, which serves as a reverse proxy to our backend services, mediasoup server and session server. NGINX also load balances any number of instances we have for the session server.

How to spin up development environment:

cd server
docker-compose up --build //spins up Redis server
npm run dev //in diff terminal tab

cd rtc-server
npm run dev

cd client
npm start

How to emulate production environment (diff docker processes on local machine):

• Change rtcServerDomain to http://localhost:5000 in /client/src/utils/rtc-socket-client.ts (will figure out a way to make this automatic based on environment)
• Navigate back to root directory

docker-compose up --build

cd client
npm start

How to test with more sessionServer instances: docker-compose up -d --scale sessionServer=3