Add infinite loading to Select descriptors step

Please add infinite loading to Dataset "Traits" step and Descriptor list's "Select descriptor" step.

Descriptors paged can be stored at state.datasets.dashboard.descriptors as we do with accessionRefs

Also please delete unused pagination from those components:

pagination: new Pagination<DescriptorFilter>({
    page: +parse(ownProps.location.search).p || 0, // current page
    size: +parse(ownProps.location.search).l || 20, // page size
    sort: parse(ownProps.location.search).s, // page sorts
    dir: parse(ownProps.location.search).d, // page sort directions
  }),