Determine whether to support activities in multi window (1/n)

Add a field of supportsMultiWindow to TaskInfo for WM Shell to use.

Because we will change to Task#supportsMultiWindow to check the
support based on the root activity's resizibilty, min widht/height,
and the device settings, using this to replace the check in
ActivityTaskManager, which is pure device settings.

Bug: 176061101
Test: atest WMShellFlickerTests
Change-Id: Iad94b39506e71b6224d923f02bd7fc454cae02c8