Anton/sync groups and verticals

This fixes https://openedx.atlassian.net/browse/BLD-1095

NB: before merge `ENABLE_GROUP_CONFIGURATIONS` should be set to default value.

Please review: @tymofij  @cahrens 
gr

> The method that you're using here, of synchronizing them whenever the split test renders, will result in many more updates to the contents than are actually required.

Yes, a bit more, not many more: it will work only in Studio, and only on split test component page