[Provider Model] Internet Picker implementation.

 Show mobile network on internet page

 With mobile network
  - https://screenshot.googleplex.com/7HzGhnbpitErynY

 Without mobile network
  - https://screenshot.googleplex.com/8sNVggTpKEhKeRh

Class diff: https://diff.googleplex.com/#key=WosyTF0ANVMf

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

Bug: 173105859
Test: atest NetworkMobileProviderControllerTest passed
Test: make RunSettingsRoboTests ROBOTEST_FILTER=SubscriptionsPreferenceControllerTest passed

Change-Id: I9671a0b85aad1dd2f53772539505b0ad96edbda3