editor - use bulk descriptor update API

[gashcrumb]

This is a...

[x] Feature request
[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[ ] Documentation issue or request

Description

When adding the split step we had to add a backend API so that the UI could fetch updated data shape info for the split step. Since then a bulk descriptor update operation has been introduced, we should port the changes that were done to the angular app to the react editor. The PR where this was done is here and the original bulk API was added here

[gashcrumb]

@christophd if you fancy getting familiar with the react codebase this could be a gateway :-)

[gashcrumb]

My first inclination would be to add a function to call the bulk api from this file and then actually make that call from before here and before here