Stages/waagent.conf: support additional options

Extend the stage to support setting new options:
 - Provisioning.UseCloudInit
 - Provisioning.Enabled

Extend the stage test to use them and add a simple stage unit test for
the schema.

Related to https://github.com/osbuild/images/issues/1416

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

test/data/stages/waagent.conf/b.json

@@ -681,6 +681,8 @@
           "type": "org.osbuild.waagent.conf",
           "options": {
             "config": {
+              "Provisioning.UseCloudInit": true,
+              "Provisioning.Enabled": false,
               "ResourceDisk.Format": false,
               "ResourceDisk.EnableSwap": true
             }

test/data/stages/waagent.conf/b.mpp.yaml

@@ -30,6 +30,8 @@ pipelines:
       - type: org.osbuild.waagent.conf
         options:
           config:
+            Provisioning.UseCloudInit: true
+            Provisioning.Enabled: false
             ResourceDisk.Format: false
             ResourceDisk.EnableSwap: true
       - type: org.osbuild.waagent.conf

test/data/stages/waagent.conf/diff.json

@@ -5,7 +5,7 @@
     "/etc/waagent.conf": {
       "content": [
         "sha256:9908ed1eeb7f4cd29ef3f1baa4f87d1de6ad6adaa08a09d83861a4a1fb88fb3a",
-        "sha256:7551a6a82c9133811b3e1a22504250fe8ced1f3bd4b47b14fceed028316ef5f5"
+        "sha256:746a295fa3c6aa3d90295611a55401d6c4b0bff1d2bbc5fb45ec4112bee84354"
       ]
     }
   }