Fix remaining Angular 22 upgrade errors

Gives `SpotFormBindingDirective` an explicit constructor, as Angular 22
rejects constructor inheritance from the undecorated `NgControl` base
class (NG2006).

Coerces `hidden` to a boolean in the OpenID Connect providers
controller, as TypeScript 6.0's DOM types widen the getter to include
string values.

Author: myabc

frontend/src/app/spot/components/form-field/form-binding.directive.ts

@@ -17,6 +17,10 @@ export const formControlBinding = {
 export class SpotFormBindingDirective extends NgControl {
   @Input('spotFormBinding') form!:UntypedFormControl|UntypedFormGroup|UntypedFormArray;
 
+  constructor() {
+    super();
+  }
+
   get control():UntypedFormControl|UntypedFormGroup|UntypedFormArray {
     return this.form;
   }

frontend/src/stimulus/controllers/dynamic/admin/openid-connect-providers.controller.ts

@@ -13,6 +13,6 @@ export default class OpenidConnectProvidersController extends Controller {
     this
       .azureFormTarget
       .querySelectorAll('input')
-      .forEach((el) => (el.disabled = this.azureFormTarget.hidden));
+      .forEach((el) => (el.disabled = this.azureFormTarget.hidden === true));
   }
 }