Backend changes for Experiment redesign

[bcb37]

• Create 6 new endpoints for experiment lists:

  • Add Experiment Inclusion
  • Edit Experiment Inclusion
  • Delete Experiment Inclusion
  • Add Experiment Exclusion
  • Edit Experiment Exclusion
  • Delete Experiment Exclusion

• Alter the existing Experiment edit/add endpoints to not operate on the inclusion/exclusion lists

• Change the entity definitions for Experiment, ExperimentSegmentInclusion, and ExperimentSegmentExclusion to reflect the new 'OneToMany'/'ManyToOne' relationship - (also add the 'enabled' attribute to the Inclusion/Exclusion entities - if we're using that, which will require a db schema migration)

• Add 'Draft' to the Experiment State enumerations in the database and the type definitions - will require a db schema migration

• Other changes as the need arises

NOTE: For backward compatibility with existing experiments, we'll have to include some of the old UI to use for editing/displaying old-style experiment lists, similarly to what we had to do for segments. If an experiment list has a 'listType' of null, we can use the old UI to edit or view it.