WindowInfo: Merge InputConfig and Feature flags

Merge the two flags in native code. We move the InputConfig flag
defintions to AIDL since we will be using the flags in Java as part of
the InputWindowHandle API next.

InputFeatureFlags are now a WM-only flag, but is temporarily used by
InputWindowHandle until the cleanup is completed.

Bug: 216806304
Test: atest libgui_test
Test: atest inputflinger_tests
Change-Id: I82d6de35b30d9cd4bcaf61499216c8faf407e885