✨ feat(server): Add startup script (#63)

## Description

**What issue are you solving (or what feature are you adding) and how
are you doing it?**

We start the container using supervisord, which is limiting as the user
has no way of telling the container what game to run. So, the idea is to
run like so: `docker run... ghcr.io/netrisdotme/netris/server:<tag>
netris-proton /game/yourgame.exe`


Co-authored by @djpremier

dev/build.sh

@@ -0,0 +1,3 @@
+#!/bin/bash -e
+
+docker build -t server -f server.Dockerfile .