Make NTP config configurable from cmd

Enable NTP failure / timeout testing by providing an ability for testers
to change the NTP configuration. Also improve debugging information from
dumpsys and logs.

Testing:

adb shell cmd network_time_update_service set_server_config --hostname localhost
adb shell dumpsys network_time_update_service
adb shell cmd network_time_update_service force_refresh
<observe false>

adb shell dumpsys network_time_update_service
adb shell cmd network_time_update_service set_server_config --hostname localhost --timeout_millis 1000
adb shell dumpsys network_time_update_service
adb shell cmd network_time_update_service force_refresh
<observe false, but faster>

adb shell cmd network_time_update_service set_server_config --hostname localhost --timeout_millis 10000
adb shell dumpsys network_time_update_service
adb shell cmd network_time_update_service force_refresh
<observe false, but slower>

adb shell cmd network_time_update_service set_server_config
adb shell cmd network_time_update_service force_refresh
<observe true>

Bug: 213393821
Test: See above
Change-Id: Ic66c7fabe0b42a3d5c86f8b85f17096bf64a8209