fix(modal): remove close button title attribute, add aria-hidden to icons (#1308)

* fix(modal): close button should not have a title

* fix(modal): close icon should not have aria-label

* fix(modal): close button icons should have `aria-hidden="true"

src/ComposedModal/ModalHeader.svelte

@@ -50,13 +50,16 @@
   <slot />
   <button
     type="button"
-    title="{iconDescription}"
     aria-label="{iconDescription}"
     class:bx--modal-close="{true}"
     class="{closeClass}"
     on:click
     on:click="{closeModal}"
   >
-    <Close size="{20}" class="bx--modal-close__icon {closeIconClass}" />
+    <Close
+      size="{20}"
+      class="bx--modal-close__icon {closeIconClass}"
+      aria-hidden="true"
+    />
   </button>
 </div>