stages/cloud-init: add support for configuring Azure datasource

Datasources are defined in an array to preserve ordering and are then
converted to objects.

stages/org.osbuild.cloud-init

@@ -57,6 +57,31 @@ SCHEMA = r"""
             }
           }
         }
+      },
+      "datasource_list": {
+        "type": "array",
+        "items": {
+          "type": "string",
+          "enum": ["Azure"]
+        }
+      },
+      "datasource": {
+        "type": "object",
+        "description": "Sources of configuration data for cloud-init.",
+        "minProperties": 1,
+        "properties": {
+          "Azure": {
+            "type": "object",
+            "minProperties": 1,
+            "properties": {
+              "apply_network_config": {
+                "type": "boolean",
+                "description": "Whether to use network configuration described by Azure’s IMDS endpoint",
+                "default": true
+              }
+            }
+          }
+        }
       }
     }
   }