refactor!(tmpfiles): expand power upon tmpfiles by deabstracting

This returns tmpfiles to its original form. Turns out that
making something too simple gives it less power.

hosts/solterra/users/artur/configs/river/scripts/waybar.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+pid="$(pidof waybar)"
+
+if [[ -z $pid ]]; then
+	exec waybar &
+fi