[FIX] Moved predefined margin classes to core package

Change-Id: Ia987b03ea371e41683beb67feebb5fc021d48b7b
CR-Id: 012006153200015135692014
[FIX] ListBox: Issue with DropdownBox inside Popup

BCP: 1482019919
Change-Id: Idd17a8cf9e46fbdc3c56d5176c4eacb0829a203a
(cherry picked from commit 4c5944529f116f625b17a23710c1a7f515fca112)
CR-Id: 012006153200015147052014
Merge "[FIX] Moved predefined margin classes to core package" into rel-1.26