Restricted status bar system icons touch handling to mouse events

As part of systemUI work to support mouse usage, system icons in status
bar recently became clickable and hence started handling touches, both
pointer(mouse) touches and finger touches (unintentionally). This led to
system icons container stealing touches from statusbar making it
impossible to swipe down from the system icons area to expand shade.

To fix this, we've restriced system icons container touch handling to
strictly mouse events hence all finger touch interactions stay the same
and mouse click touches are handled as intended.

Test: atest PhoneStatusBarViewControllerTest
Flag: NA
Fixes: 326097469
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:8fa136dadcafb504e9f370347e39b84ba87c0cfe)
Merged-In: Ib1dc596311e1d8e737982cf6201a66481daef75a
Change-Id: Ib1dc596311e1d8e737982cf6201a66481daef75a