fix(material/timepicker): hide toggle icon from assistive technology

Fixes that the timepicker toggle icon was being read out as an image.

Author: crisbeto

src/material/timepicker/timepicker-toggle.html

@@ -14,7 +14,9 @@
       height="24px"
       width="24px"
       viewBox="0 -960 960 960"
-      fill="currentColor">
+      fill="currentColor"
+      focusable="false"
+      aria-hidden="true">
       <path d="m612-292 56-56-148-148v-184h-80v216l172 172ZM480-80q-83 0-156-31.5T197-197q-54-54-85.5-127T80-480q0-83 31.5-156T197-763q54-54 127-85.5T480-880q83 0 156 31.5T763-763q54 54 85.5 127T880-480q0 83-31.5 156T763-197q-54 54-127 85.5T480-80Zm0-400Zm0 320q133 0 226.5-93.5T800-480q0-133-93.5-226.5T480-800q-133 0-226.5 93.5T160-480q0 133 93.5 226.5T480-160Z"/>
     </svg>
   </ng-content>