Reports resizing state to WM core so that app client could apply bigger
visible bounds while resizing splits. Also moves DividerHandleView to
more generic package.
Fix: 172704238
Test: manul check divider behavior
Test: atest WMShellUnitTests
Change-Id: I1656c86de9a0b5dfe5e6da57ccc9d5f6e467843a
Update SplitLayout and DividerView to support dragging divider bar and
make them more generic to be able to share among different split impl.
Bug: 172704238
Test: manual check the behavior of divider bar
Test: atest WMShellUnitTests
Change-Id: I16ed1fd86bdff4d8544c5787c95315c59055ad04
Add divider bar for app-pairs. AppPairLayout and divide policy records
and handles the layout in pair.
Bug: 172704238
Bug: 172704672
Test: manul check the behavior of the splits and divider bar.
Test: AppPairTests, AppPairsPoolTests, AppPairsControllerTests
Change-Id: I688c7001d056fe8dd9a192885e1f9fd5f004dc11