ci: Build and publish system extensions

Use gnomeos-build-sysext CI/CD component to build a system
extension out of mutter branches and MRs.

Use the common script for installing dependencies, but keep
a separate gnomeos script for exclusive dependencies.

See https://discourse.gnome.org/t/towards-a-better-way-to-hack-and-test-your-system-components/21075
See https://gitlab.gnome.org/GNOME/gnome-build-meta/-/issues/837

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3843>

.gitlab-ci.yml

@@ -3,6 +3,15 @@ include:
   - remote: 'https://gitlab.freedesktop.org/freedesktop/ci-templates/-/raw/34f4ade99434043f88e164933f570301fd18b125/templates/ci-fairy.yml'
   - project: 'Infrastructure/openshift-images/gnome-release-service'
     file: '/ci-templates/release-module.yml'
+  - component: gitlab.gnome.org/GNOME/citemplates/gnomeos-build-sysext@1.0.0-alpha
+    inputs:
+      meson-options:
+        -Dxwayland_initfd=enabled
+        -Dprofiler=true
+
+build-sysext:
+  before_script:
+    - .gitlab-ci/install-gnomeos-sysext-dependencies.sh $CI_PROJECT_DIR/extension
 
 stages:
  - review

.gitlab-ci/install-gnomeos-sysext-dependencies.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+set -e
+
+SCRIPTS_DIR="$(dirname $0)"
+
+# Location for dependencies to be bundled with the extension
+DESTDIR="$(realpath $1)"
+
+# GNOME OS specific setup arguments
+LIBDIR="lib/$(gcc -print-multiarch)"
+
+# Install common dependencies
+./$SCRIPTS_DIR/install-common-dependencies.sh --libdir=$LIBDIR --destdir=$DESTDIR
+
+# Install below missing dependencies that are exclusive to GNOME OS