Fix wrong app is launched after solving challenge from tapping notification

PendingIntent.FLAG_ONE_SHOT is needed to prevent the PendingIntent being
reused.

Also, flag and activity option of credential intent in BaseStatusBar
is not same as the one in ActivityStarter. Added a new
function startConfirmDeviceCredentialIntent in AM to centralize it.

Change-Id: I2d9e5923ad5d4d012f10057c409c666c8ca299a3
Fix: 28309964