docs: use BooleanInput in examples for custom control (#21913)

(cherry picked from commit ddb206e)

Author: AlexElin

src/components-examples/material-experimental/mdc-form-field/mdc-form-field-custom-control/form-field-custom-control-example.ts

@@ -1,5 +1,5 @@
 import {FocusMonitor} from '@angular/cdk/a11y';
-import {coerceBooleanProperty} from '@angular/cdk/coercion';
+import {BooleanInput, coerceBooleanProperty} from '@angular/cdk/coercion';
 import {Component, ElementRef, Inject, Input, OnDestroy, Optional, Self} from '@angular/core';
 import {ControlValueAccessor, FormBuilder, FormGroup, NgControl, Validators} from '@angular/forms';
 import {MatFormField, MatFormFieldControl} from '@angular/material-experimental/mdc-form-field';
@@ -153,6 +153,6 @@ export class MyTelInput implements ControlValueAccessor, MatFormFieldControl<MyT
     this.onChange(this.value);
   }
 
-  static ngAcceptInputType_disabled: boolean | string | null | undefined;
-  static ngAcceptInputType_required: boolean | string | null | undefined;
+  static ngAcceptInputType_disabled: BooleanInput;
+  static ngAcceptInputType_required: BooleanInput;
 }

src/components-examples/material/form-field/form-field-custom-control/form-field-custom-control-example.ts

@@ -1,5 +1,5 @@
 import {FocusMonitor} from '@angular/cdk/a11y';
-import {coerceBooleanProperty} from '@angular/cdk/coercion';
+import {BooleanInput, coerceBooleanProperty} from '@angular/cdk/coercion';
 import {
   Component,
   ElementRef,
@@ -224,6 +224,6 @@ export class MyTelInput
     this.onChange(this.value);
   }
 
-  static ngAcceptInputType_disabled: boolean | string | null | undefined;
-  static ngAcceptInputType_required: boolean | string | null | undefined;
+  static ngAcceptInputType_disabled: BooleanInput;
+  static ngAcceptInputType_required: BooleanInput;
 }