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/nixos/dotfiles/notmuch-config

@@ -0,0 +1,21 @@
+# .notmuch-config - Configuration file for the notmuch mail system
+#
+# For more information about notmuch, see https://notmuchmail.org
+
+[database]
+path=/home/vincent/mail
+
+[user]
+name=Vincent Ambo
+primary_email=mail@tazj.in
+other_email=tazjin@gmail.com;
+
+[new]
+tags=unread;inbox;
+ignore=
+
+[search]
+exclude_tags=deleted;spam;draft;
+
+[maildir]
+synchronize_flags=true