Prevent Overview Actions from appearing during split from home

Overview Actions will no longer erroneously appear when initiating a split from home.

The bug occurred because split from home causes an irregular state where the user is in split select, yet there is still a focused (main) task in Overview. Overview Actions did not anticipate this state and had no case to handle it.

Fixed by adding a check to Overview Actions so that they will never show when split selection is active.

Fixes: 244499708
Test: Manual
Change-Id: Idf1762c306dceb5048cefec8fa68ac9ca5468379