[Provider Model] Show all carrier's name on MobileNetworkSummaryController's summary

Screenshot of Provider Model: https://screenshot.googleplex.com/6mKLeMWGWZJh86u.png

Screenshot of current: https://screenshot.googleplex.com/Abncb2QGh5TWxEv.png

Doc: https://docs.google.com/presentation/d/1azrZVS54pxM2lt9LkZHtFh_6W3fyDw_kTTPVQ_mJCi4/edit#slide=id.g9c7123c172_0_448

Bug: 172229551
Test: manual and make RunSettingsRoboTests ROBOTEST_FILTER=MobileNetworkSummaryControllerTest

Change-Id: I0f2a23659ef80b6a76b34af9503ad8d746967859