Port stylus shutdown fix from 4.8

[SamBent]

Addresses Issue #4982. This is a port from a servicing fix in .NET 4.7-4.8.

Description

HwndSource shuts down its stylus stack when it receives WM_DESTROY. In the repro it doesn't receive WM_DESTROY, and therefore leaks many resources associated with stylus/touch including the HwndSource object itself, but most notably the handles used for communication with WISP.

More precisely, the logic for WM_DESTROY lives in the PublicHooks message filter, which is only called if public hooks have been added to the HwndSource. All the places where WPF itself creates the HwndSource add hooks - the chief examples are Window and Popup - so "normal" apps don't leak. But the repro creates HwndSource directly and doesn't add hooks, hence it leaks.

Fixed by adding WM_DESTROY logic to the Input message filter, which is always called (unless a public hook handles the WM_DESTROY message).

Customer Impact

App eventually crashes when it runs out of handles.

Regression

Introduced in 4.7.

Testing

Ad-hoc around customer scenario.
Standard regression testing

Risk

Low. Port of a .NETFx servicing fix released earlier this year.