[21/n Dispatcher refactor] Make touchStatesByDisplay private

In this Cl we make mTouchStatesbyDisplay private in
DispatcherTouchState. For this we need to
1. Move canWindowReceiveMotion as a private method in the
DispatcherTouchState along with isStylusActiveInDisplay.
2. Make findTouchedSpyWindowsAt static moving it back to Dispatcher.

Bug: 367661487
Bug: 245989146
Test: atest inputflinger_tests
Flag: EXEMPT refactor
Change-Id: Ifc970b091b90cbeaf41d4932415417b161c2ae34