Properly launch quicksettings activities.

 - As current user
 - Dismissing keyguard if necessary
 - Dismissing all status bar windows and panels

Also move some QS-specific stuff out of PanelView and into
SettingsPanelView.

Bug: 7217006
Change-Id: I4d8ac84cc0f43e78f70553599c3207305c4f5c74