refactor(core): handle angular#24571 todos

Author: RafaelJCamara

packages/common/http/test/jsonp_mock.ts

@@ -28,15 +28,14 @@ export class MockScriptElement {
 }
 
 export class MockDocument {
-  // TODO(issue/24571): remove '!'.
-  mock!: MockScriptElement | null;
+  mock: MockScriptElement | null = null;
   readonly body: any = this;
 
   implementation = {
     createHTMLDocument: () => new MockDocument(),
   };
 
-  createElement(tag: 'script'): HTMLScriptElement {
+  createElement(): HTMLScriptElement {
     return new MockScriptElement(this) as any as HTMLScriptElement;
   }
 

packages/forms/src/directives/abstract_form_group_directive.ts

@@ -30,7 +30,6 @@ export class AbstractFormGroupDirective extends ControlContainer implements OnIn
    *
    * @internal
    */
-  // TODO(issue/24571): remove '!'.
   _parent!: ControlContainer;
 
   /** @nodoc */

packages/forms/src/directives/ng_form.ts

@@ -160,8 +160,7 @@ export class NgForm extends ControlContainer implements Form, AfterViewInit {
    * Possible values: `'change'` | `'blur'` | `'submit'`.
    *
    */
-  // TODO(issue/24571): remove '!'.
-  @Input('ngFormOptions') options!: {updateOn?: FormHooks};
+  @Input('ngFormOptions') options?: {updateOn?: FormHooks};
 
   constructor(
     @Optional() @Self() @Inject(NG_VALIDATORS) validators: (Validator | ValidatorFn)[],

packages/forms/src/directives/ng_model.ts

@@ -196,8 +196,7 @@ export class NgModel extends NgControl implements OnChanges, OnDestroy {
    * @description
    * Tracks whether the control is disabled.
    */
-  // TODO(issue/24571): remove '!'.
-  @Input('disabled') isDisabled!: boolean;
+  @Input('disabled') isDisabled?: boolean;
 
   /**
    * @description
@@ -221,8 +220,7 @@ export class NgModel extends NgControl implements OnChanges, OnDestroy {
    * Defaults to 'change'. Possible values: `'change'` | `'blur'` | `'submit'`.
    *
    */
-  // TODO(issue/24571): remove '!'.
-  @Input('ngModelOptions') options!: {name?: string; standalone?: boolean; updateOn?: FormHooks};
+  @Input('ngModelOptions') options?: {name?: string; standalone?: boolean; updateOn?: FormHooks};
 
   /**
    * @description

packages/forms/src/directives/select_multiple_control_value_accessor.ts

@@ -44,19 +44,6 @@ function _extractId(valueString: string): string {
   return valueString.split(':')[0];
 }
 
-/** Mock interface for HTML Options */
-interface HTMLOption {
-  value: string;
-  selected: boolean;
-}
-
-/** Mock interface for HTMLCollection */
-abstract class HTMLCollection {
-  // TODO(issue/24571): remove '!'.
-  length!: number;
-  abstract item(_: number): HTMLOption;
-}
-
 /**
  * @description
  * The `ControlValueAccessor` for writing multi-select control values and listening to multi-select