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)

web/tazblog/default.nix

@@ -0,0 +1,18 @@
+# Build configuration for the blog using plain Nix.
+#
+# tazblog.nix was generated using cabal2nix.
+
+{ pkgs, ... }:
+
+let
+  inherit (pkgs.third_party) writeShellScriptBin haskell;
+  tazblog = haskell.packages.ghc865.callPackage ./tazblog.nix {};
+  wrapper =  writeShellScriptBin "tazblog" ''
+    export PORT=8000
+    export RESOURCE_DIR=${./static}
+    exec ${tazblog}/bin/tazblog
+  '';
+in wrapper.overrideAttrs(_: {
+  allowSubstitutes = true;
+  meta.enableCI = true;
+})