Don't reset RecentsView in onIdpChanged()

Resetting unloads visible task data and thus will leave recents
blank if overview state is enabled. Instead, unload and reload
visible task data to take new icon shape into account.

(The reason we're getting onIdpChanged() on nav bar mode change
is because the change in nav bar height causes the computed icon
size to change very slightly.)

Also fix InvariantDeviceProfile copy constructor by copying
iconBitmapSize.

Test:
- Change between 0 button and 3 button nav modes, verify recents
  doesn't appear blank
- Change icon shape in Styles and Wallpapers and go to recents,
  verify icon shape is reflected in task icons

Bug: 156354328
Change-Id: Ife29f51e85814ff483d055005fa2645135d5ec3d