Deprecate SPI related to internal compactions

[keith-turner]

Functionality related to internal compactions will be removed. The methods and types related to this in the SPI could be deprecated in 3.0 after its know what will be removed from the SPI

[keith-turner]

As part of this work, the configuration of the default planner will need to be updated as mentioned in a comment on #3460

[keith-turner]

Also need to remove the concept of internal compactions from the SPI in elasticity branch.

[ddanielr]

@keith-turner I can work on this as prep step for #3635 and #3547 as it would cleanup the remaining code that needs to be modified.

[ddanielr]

Current list of items to change in SPI:

CompactionExecutorId (Deprecated)
CompactionGroupId (new class)
CompactionJob (method change)
CompactionPlan (Doc Change)
CompactionPlanner (Method modification)
DefaultCompactionPlanner ( Large rewrite)
DefaultCompactionPlannerTest ( Large rewrite)
GroupManager (new class)
ExecutorManager (Deprecated)