Add service side help commands to shell 'help' command

Test: atest AdServicesShellCommandTest
Test: adb shell device_config put adservices adservices_shell_command_enabled true && adb shell cmd adservices_manager
      adb shell cmd adservices_manager
Bug: 308009734

Change-Id: I2c1ff9140357cbd3eaa185e3a026771cb44089a3
3 files changed