Unsingletonize UsersViewModel, so it load different view on lockscreen

Currently UsersViewModel is a singleton which does not
allow to display UI dependent to lock screen permission
This change is replacing it with non-singleton data and
replace the refresh mechanism using SharedStateFlow.

Bug:431999010
Test: manual
Flag: EXEMPT Bugfix
Change-Id: I5261147c441715f6f4b76af193278fefce5432ce
3 files changed