Remove the overridden schema for new work packages once saved

We still have components that use a new work package and its form schema
set by the `overriddenSchema` property. We should get rid of this
and instead let them use the edit resource in the long run.

frontend/app/components/api/api-v3/hal-resources/work-package-resource.service.ts

@@ -124,6 +124,7 @@ export class WorkPackageResource extends HalResource {
   public attachments:AttachmentCollectionResourceInterface;
 
   public pendingAttachments:UploadFile[] = [];
+  public overriddenSchema?:SchemaResource;
 
   public get id():string {
     return this.$source.id || this.idFromLink;

frontend/app/components/wp-edit-form/work-package-changeset.ts

@@ -61,9 +61,14 @@ export class WorkPackageChangeset {
       'wpCacheService', 'wpCreate'
     );
 
-    // Start with a resource from the current work package knowledge.
-    const payload = this.mergeWithPayload(workPackage.$plain);
-    this.buildResource(payload);
+    if (this.workPackage.isNew) {
+      // New work packages have no schema set yet, so update the form immediately to get one
+      this.updateForm();
+    } else {
+      // Start with a resource from the current work package knowledge.
+      const payload = this.mergeWithPayload(workPackage.$plain);
+      this.buildResource(payload);
+    }
   }
 
   public startEditing(key:string) {
@@ -185,6 +190,7 @@ export class WorkPackageChangeset {
               this.workPackage.updateActivities();
 
               if (wasNew) {
+                this.workPackage.overriddenSchema = undefined;
                 this.workPackage.uploadAttachmentsAndReload();
                 this.wpCreate.newWorkPackageCreated(this.workPackage);
               }