* Add functionality to decide whether front-end should be served from server
This commit makes the server allow flag `--serve-frontend`, providing
which, will make the server serve the front-end at route '/'. Otherwise
it won't serve the front-end.
* Use env variable to enable serving client from a server end-point
* Add documentation for SERVE_CLIENT env var
* separate dockerfile for tooljet client in development mode
* production dockerfile for tooljet client
* reference the tooljet clients dev dockerfile in the docker-compose file
* use a fallback url for API_URL in cases where TOOLJET_SERVER_URL is not defined
* nginx config file for the front-end
* docker-compose file for production deploys
* dont run postgres inside docker-compose
* use an entrypoint script for setting the server host for nginx
* separate volume for fallback certs
* add docs for docker-compose deployment
* add required database keys in the .env.example file
* address review comments
