Restrict ChooserTargets provided by a single service

Only allow one row's worth of targets from any one
ChooserTargetService and lower the weight for app recency in resolver
sorting. Along with a previous change to only consider the past 1 week
of app activity, this is to help improve the quality of direct share
targets shown.

Bug 26562857

Change-Id: I0f9a8ca8ccfb655261421e29fef7909cadd318f1