Pull all current role holders into statsd

Create a new atom RoleHolder that maps a uid -> role and add the
mappings that currently exist in RoleManagerService

Test: - ./out/host/linux-x86/bin/statsd_testdrive 10049
      - adb shell cmd stats pull-source 10049
Bug: 123594188
Change-Id: Ib0fa60b07a95c06a219f3e3b37d51f59b624a017