chore: fix typo in MDC skeleton code (#15863)

Author: mmalerba

src/material-experimental/mdc-button/button.ts

@@ -16,7 +16,7 @@ import {ChangeDetectionStrategy, Component, ViewEncapsulation} from '@angular/co
   host: {
     'class': 'mat-mdc-button',
   },
-  exportAs: 'matMyCheckbox',
+  exportAs: 'matButton',
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })

src/material-experimental/mdc-card/card.ts

@@ -16,7 +16,7 @@ import {ChangeDetectionStrategy, Component, ViewEncapsulation} from '@angular/co
   host: {
     'class': 'mat-mdc-card',
   },
-  exportAs: 'matMyCheckbox',
+  exportAs: 'matCard',
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })

src/material-experimental/mdc-menu/menu.ts

@@ -16,7 +16,7 @@ import {ChangeDetectionStrategy, Component, ViewEncapsulation} from '@angular/co
   host: {
     'class': 'mat-mdc-menu',
   },
-  exportAs: 'matMyCheckbox',
+  exportAs: 'matMenu',
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })

src/material-experimental/mdc-radio/radio.ts

@@ -16,7 +16,7 @@ import {ChangeDetectionStrategy, Component, ViewEncapsulation} from '@angular/co
   host: {
     'class': 'mat-mdc-radio',
   },
-  exportAs: 'matMyCheckbox',
+  exportAs: 'matRadio',
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })

src/material-experimental/mdc-slide-toggle/slide-toggle.ts

@@ -16,7 +16,7 @@ import {ChangeDetectionStrategy, Component, ViewEncapsulation} from '@angular/co
   host: {
     'class': 'mat-mdc-slide-toggle',
   },
-  exportAs: 'matMyCheckbox',
+  exportAs: 'matSlideToggle',
   encapsulation: ViewEncapsulation.None,
   changeDetection: ChangeDetectionStrategy.OnPush,
 })