Created a mechanism to dump service-less SystemServer state.

SystemServer has classes (like SystemServerInitThreadPool,
SystemServiceManager, and even SystemServer itself) that are
not associated with a service; hence, the state of these classes
are not dumped in a bugreport.

Test: adb shell dumpsys system_server_dumper
Test: adb shell dumpsys system_server_dumper --list
Test: adb shell dumpsys system_server_dumper --name SystemServer

Bug: 159831354
Fixes: 163921395

Change-Id: I5719f7cd3a9022dc0ab12a3b3b22487e2b4866e0