Sidecar to Daemonset

[dgkanatsios]

PR to remove the sidecar in favor of a DaemonSet. Fixes #107. TODO items:

• Protect the DaemonSet HTTP server by ListenAndServer on the Node DNS Name. We need to make sure this works with kind as well. Another option would be to somehow configure the DaemonSet Pods (either configuration or code?) to NOT accept traffic from outside the Node
• Decide how we're gonna have a single .Update on the GameServer controller loop - we fixed this by using Patch. A subsequent PR will update the controller code with patch instead of update
• Change the documentation and the architecture image from sidecar to DaemonSet
• end to end tests should wait for the DaemonSet to start (kubectl wait didn't seem to work). We will not do that after all, since in production environments, DaemonSet Pods will be scheduled before GameServer Pods but they may not start before them. Worst case scenario, we might miss a couple of heartbeats, which is acceptable.
• write unit tests for the DaemonSet
• refactor DaemonSet code to use a struct so we can do DI on the tests
• modify the end to end tests to check DaemonSet for the player logs instead of the sidecar
• have the DaemonSet start before other pods in the Node start (we should check https://kubernetes.io/docs/concepts/scheduling-eviction/pod-priority-preemption/#effect-of-pod-priority-on-scheduling-order, thanks @khaines)
• In case of multiple Node Pools, how can we update DaemonSet to be scheduled only on the Node Pools that have Game Servers? yup, Node Selectors https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/#running-pods-on-select-nodes
• Add healthz to the web server

[khaines]

A few nits, but nothing blocking related to this change. Glad to see this getting merged in!

[khaines]

Nit: I like the comment at the top of the old file describing what the intent is