Add the print service recommendation service

This service connects through the print manager to the print spooler:

PrintSpooler.AddPrintersActivity <-> PrintManager <-> PrintManagerService <-> UserState <-> RemotePrintServiceRecommendationService <-> PrintRecommendationService <-> PrintRecommendationServiceImpl

Hence there is a lot of mindless plumming.

The actual changes are only in the AddPrintersActivity which is extended
to show another list of services: The recommended services.

The PrintServiceRecommendationService is based on the experimenal print
service stubs provider. This provider was contributed the Android by
Mopria. As this services uses Android own network discovery service most
code from the experimental provider goes away. In fact the only logic
left over is the selections of mdns-txt fields to look at and the
printer vendor configuration.

This relies on the Android MDNS to get fixed (Bug: 27696905). This also
does not deal with how to update the recommendation service.

Bug: 24533249
Change-Id: I6edc6e25fc08a50d478b61c71bb8ea158b08624c