stages/locale: Refactor locale stage to look like similar ones

The locale stage now cannot be used to set the keymap. Use the keymap
stage instead. Also, the stage was refactored to look like keymap and
timezone stages just to be consistent (systemd-firstboot is now used).

test/__main__.py

@@ -28,6 +28,12 @@ def test_firewall(extract_dir):
         assert 'port port="88" protocol="udp"' in content
 
 
+def test_locale(extract_dir):
+    with open(f"{extract_dir}/etc/locale.conf") as f:
+        content = f.read()
+        assert 'LANG=nn_NO.utf8' in content
+
+
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(description='Run integration tests')
     parser.add_argument('--list', dest='list', action='store_true', help='list test cases')
@@ -64,8 +70,16 @@ if __name__ == '__main__':
         test_cases=[test_firewall],
         type=IntegrationTestType.EXTRACT
     )
+    locale = IntegrationTestCase(
+        name="locale",
+        pipeline="locale.json",
+        build_pipeline=args.build_pipeline,
+        output_image="locale.tar.xz",
+        test_cases=[test_locale],
+        type=IntegrationTestType.EXTRACT
+    )
 
-    cases = [f30_boot, timezone, firewall]
+    cases = [f30_boot, timezone, firewall, locale]
 
     if args.list:
         print("Available test cases:")

test/pipelines/locale.json

@@ -0,0 +1,32 @@
+{
+  "name": "Example Image",
+  "stages": [
+    {
+      "name": "org.osbuild.dnf",
+      "options": {
+        "releasever": "30",
+        "repos": {
+          "fedora": {
+            "name": "Fedora",
+            "metalink": "https://mirrors.fedoraproject.org/metalink?repo=fedora-$releasever&arch=$basearch",
+            "gpgkey": "file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora-$releasever-$basearch"
+          }
+        },
+        "packages": ["@Core"]
+	}
+    },
+    {
+      "name": "org.osbuild.locale",
+      "options": {
+        "language": "nn_NO.utf8"
+      }
+    }
+  ],
+  "assembler": {
+    "name": "org.osbuild.tar",
+    "options": {
+      "filename": "locale.tar.xz",
+      "compression": "xz"
+    }
+  }
+}