Throw IllegalArgumentException when calling setNightModeCustomType with an unsupported type

Also
1. update documentation about the IllegalArgumentException thrown in
   setNightModeCustomType
2. modify NightModeCustomType to not include MODE_NIGHT_CUSTOM_TYPE_UNKNOWN
3. add @IntDef, NightModeCustomReturnType, for the getNightModeCustomType
4. Fix lint warning

Test: atest FrameworksUiServicesTests:UiModeManagerServiceTest
Bug: 218860231
Change-Id: Id8b1f1d7a3ee60f62a0ff6cdee0b5e416a130d63