Move automatic updates by default from tier-0 to tier-1

tier-1 is more opinionated and automatic updates by default is
definitely a very strong opinion.

This makes it easier to inherit from tier-0 without having to undo that
knob if it's not desirable.

Prep for !48.

tier-1/autoupdates.yaml

@@ -0,0 +1,9 @@
+# Enable automatic updates by default
+postprocess:
+  - |
+    #!/usr/bin/env bash
+    set -euo pipefail
+    target=/usr/lib/systemd/system/default.target.wants
+    mkdir -p $target
+    set -x
+    ln -s ../bootc-fetch-apply-updates.timer $target

tier-1/manifest.yaml

@@ -3,6 +3,7 @@ recommends: true
 
 include:
   - ../tier-0/manifest.yaml
+  - autoupdates.yaml
   - bootable-rpm-ostree.yaml
   - podman.yaml
   - firmware.yaml