[SON-HIVE Voting] Implement separate son_schedule_object for Bitcoin and Hive SONs

The goal is to separate voting for Bitcoin and Hive SONs, so that they can act independently of each others. All code affected by this change should be refactored, in a way that enables that Bitcoin SON and Hive SON are considered separate entities.

This ticket covers just adding additional son_schedule_object, not putting it into use in a sidechain plugin.

The output of this task should be properly working scheduler, and nothing else.