[BottomSheet] Make touch_outside unfocusable

Resolves material-components#974

GIT_ORIGIN_REV_ID=682a8b7ac7eb4bcdc238e04c14349b7beb4a8185
PiperOrigin-RevId: 304632071

Author: Mygod

lib/java/com/google/android/material/bottomsheet/res/layout/design_bottom_sheet_dialog.xml

@@ -33,6 +33,7 @@
         android:id="@+id/touch_outside"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
+        android:focusable="false"
         android:importantForAccessibility="no"
         android:soundEffectsEnabled="false"
         tools:ignore="UnusedAttribute"/>