WIP initial steps for distributing compaction coordination

[keith-turner]

Some initial steps for distributing compaction coordinator. Currently only contains the following.

• Creates a map in ZK that maps compactor resource group to a manager process. Currently maps all RGs to the primary manager.
• Modified the compactor processes to consult this map to find which coordinator to use.
• A periodic task running in the primary manager that updates this map in ZK

Still need to do the following

• Delegate compactor resource groups to assistant managers. Will require refactoring existing code and a new RPC.
• Modify TGW to stream compaction jobs to remote assistant managers.
• Refactor all the cleanup code that runs in the coordinator to only run in the primary manager
• Potentially move the in memory tracking the coordinator currently does to the monitor.
• Correctly create the map of compactor RGs to assistant managers in ZK.

Plan to continue experimenting with this.