chore: Significantly restructure folder layout

This moves the various projects from "type-based" folders (such as
"services" or "tools") into more appropriate semantic folders (such as
"nix", "ops" or "web").

Deprecated projects (nixcon-demo & gotest) which only existed for
testing/demonstration purposes have been removed.

(Note: *all* builds are broken with this commit)

ops/infra/kubernetes/https-cert/cert.yaml

@@ -0,0 +1,8 @@
+---
+apiVersion: networking.gke.io/v1beta1
+kind: ManagedCertificate
+metadata:
+  name: {{ .domain | replace "." "-" }}
+spec:
+  domains:
+    - {{ .domain }}