[SplitButton][Button][a11y] Add content description for icon-only leading buttons.

PiperOrigin-RevId: 702046452

Author: kendrickumstattd

catalog/java/io/material/catalog/button/res/layout/cat_split_button_fragment.xml

@@ -44,6 +44,7 @@
           android:paddingStart="@dimen/m3_comp_split_button_small_leading_button_leading_space"
           android:paddingEnd="@dimen/m3_comp_split_button_small_leading_button_trailing_space"
           android:minWidth="@dimen/mtrl_min_touch_target_size"
+          android:contentDescription="@string/cat_split_button_label_edit"
           app:icon="@drawable/ic_edit_vd_theme_24dp"
           app:iconSize="20dp"
           app:iconPadding="0dp"/>
@@ -123,6 +124,7 @@
           android:paddingStart="@dimen/m3_comp_split_button_small_leading_button_leading_space"
           android:paddingEnd="@dimen/m3_comp_split_button_small_leading_button_trailing_space"
           android:minWidth="@dimen/mtrl_min_touch_target_size"
+          android:contentDescription="@string/cat_split_button_label_edit"
           app:icon="@drawable/ic_edit_vd_theme_24dp"
           app:iconSize="20dp"/>
       <Button

catalog/java/io/material/catalog/button/res/values/strings.xml

@@ -114,6 +114,7 @@
     name="cat_icon_button_label_home">Home icon</string>
   <string name="cat_split_button_label_chevron"
     description="A label for an icon-only button [CHAR LIMIT=NONE]">Chevron icon</string>
+  <string name="cat_split_button_label_edit" description="The edit icon [CHAR LIMIT=NONE]">Edit icon</string>
   <string description="A label for an icon-only button [CHAR LIMIT=NONE]"
     name="cat_icon_button_label_settings">Settings icon</string>
   <string description="A label for an icon-only button [CHAR LIMIT=NONE]"