Separate default pointer for mouse and stylus (frameworks/base part)

PointerIcon.TYPE_NOT_SPECIFIED will be used for requesting default
pointer.

For the type, MouseCursorController will decide whether to show mouse or
stylus icon, based on the active source.

Need complement: the resource for default stylus icon should be added.

Test: Manual Test(hover pointer on handwriting area)
Bug: b/215436642
Change-Id: I6a337cb69bea57427f676e561900802270d206ae