Start New Window PendingIntent as task's user

We used to use the context from the system level, and for certain
devices such as HSUM devices, these are system user context which then
will not be rendered activable by Core.

Bug: 392561846
Test: Manual, open new window
Flag: EXEMPT bug fix
Change-Id: I400b3c51832676bac8d7294894b8f39ec0965654