fix(docker): handle .env file to read frontend vars during build easily (#513)

- Remove api/.env and .env from .dockerignore file
- Add COPY .env .env to Dockerfile to copy .env file to docker build
- Add RUN rm .env to Dockerfile to remove .env file after build
- Remove build args from docker-compose.yml file

.dockerignore

@@ -1,4 +1,2 @@
 **/node_modules
-api/.env
-.env
 client/dist/images