chore: add demos for native selects in mdc-form-field

Author: devversion

src/dev-app/mdc-input/mdc-input-demo.html

@@ -720,5 +720,23 @@ <h4>Custom control</h4>
         <mat-hint>Include area code</mat-hint>
       </mat-form-field>
     </p>
+    <p>
+      <mat-form-field>
+        <mat-label>Label</mat-label>
+        <select matNativeControl>
+          <option>First</option>
+          <option>Second</option>
+        </select>
+      </mat-form-field>
+    </p>
+    <p>
+      <mat-form-field appearance="outline">
+        <mat-label>Label</mat-label>
+        <select matNativeControl>
+          <option>First</option>
+          <option>Second</option>
+        </select>
+      </mat-form-field>
+    </p>
   </mat-card-content>
 </mat-card>