Fix toolbar flickering in ExtractedMode when longpressing.

onPreDraw starts an action mode in extract mode only which
does not consider the type of motion event and since extracted
mode never gets the focus event it never hides so it does not
need to show again.

Stop starting an action mode onPreDraw in extracted mode and
let the onTouchEvent handle starting the mode.

Also re-enabled dragging and dropping for ExtractedMode (most
of the issues were caused by starting the action mode
onPreDraw).

Bug: 25102276
Change-Id: I90d8e9f42f395b6b529e4d023ba6939e0dfb147f