Rename OsuLogin package to com.android.hotspot2.osulogin

Currently, it is "com.android.hotspot2", which is
too generic, as in the future we may add more
Passpoint-related apps. Rename the package name
to be more specific.

Bug: 149589553
Test: Connecting to an OSU network automatically
opens the OsuLogin activity

Change-Id: I115a4a70379a7e897c6f82dd4eef1ef50625a6ef