Allow its WindowInfosListener to outlive PointerController

A strong pointer to PointerController::DisplayInfoListener is given away
when the listener is registered, so PC cannot guarantee that the
listener is destroyed when it is destroyed. This means the listener can
outlive PC, so there is a race condition between PC's destruction and an
update to the listener.

While it could be argued that it is the caller's responsibility to
ensure that the listener is not updated after it is unregistered, there
is no way to guarantee that using strong pointers. Here, we can be
defensive and protect against this case.

Bug: 212672261
Test: atest libinputservice_test
Change-Id: I358a725980cc8c7d6ad0483a9b2a8b8715a03424