Add calendar icon to pick date and time item.

Co-authored-by: Sgn-32 <49990901+Sgn-32@users.noreply.github.com>

app/src/main/java/org/thoughtcrime/securesms/conversation/ScheduleMessageContextMenu.kt

@@ -28,7 +28,7 @@ class ScheduleMessageContextMenu {
             action(it)
           }
         } else {
-          ActionItem(0, anchor.context.getString(R.string.ScheduledMessages_pick_time)) {
+          ActionItem(R.drawable.ic_calendar_24, anchor.context.getString(R.string.ScheduledMessages_pick_time)) {
             action(it)
           }
         }