[DnD] Update ACTION_DRAG_START coords for connected-displays

Added new tests to cover coords in single and connected
displays.
go/connected-displays-dnd

Bug: 365512241
Test: atest WmTests:DragDropControllerTests
Flag: com.android.window.flags.enable_connected_displays_dnd
Change-Id: Iaa3ae7c331fc51a2fb6f8ca0bebebea0178e2aef