chore: make orgId mandatory in CreateAppRequest (#2523)

packages/shorebird_code_push_protocol/lib/src/messages/create_app/create_app_request.dart

@@ -10,7 +10,7 @@ class CreateAppRequest {
   /// {@macro create_app_request}
   const CreateAppRequest({
     required this.displayName,
-    this.organizationId,
+    required this.organizationId,
   });
 
   /// Converts a Map<String, dynamic> to a [CreateAppRequest]
@@ -23,7 +23,6 @@ class CreateAppRequest {
   /// The display name of the app.
   final String displayName;
 
-  /// The id of organization that this app will belong to. If no id is provided,
-  /// this app will belong to the user's personal organization.
-  final int? organizationId;
+  /// The id of organization that this app will belong to.
+  final int organizationId;
 }

packages/shorebird_code_push_protocol/lib/src/messages/create_app/create_app_request.g.dart

@@ -16,7 +16,7 @@ CreateAppRequest _$CreateAppRequestFromJson(Map<String, dynamic> json) =>
         final val = CreateAppRequest(
           displayName: $checkedConvert('display_name', (v) => v as String),
           organizationId:
-              $checkedConvert('organization_id', (v) => (v as num?)?.toInt()),
+              $checkedConvert('organization_id', (v) => (v as num).toInt()),
         );
         return val;
       },

packages/shorebird_code_push_protocol/test/src/messages/create_app/create_app_request_test.dart

@@ -4,7 +4,10 @@ import 'package:test/test.dart';
 void main() {
   group(CreateAppRequest, () {
     test('can be (de)serialized', () {
-      const request = CreateAppRequest(displayName: 'display_name');
+      const request = CreateAppRequest(
+        displayName: 'display_name',
+        organizationId: 123,
+      );
       expect(
         CreateAppRequest.fromJson(request.toJson()).toJson(),
         equals(request.toJson()),