fixes #6573 - need better errors when sorting by a non-sortable field

- [x] removing `sort[by]` and `sort[order]` params
- [x] define `sortable_fields` for all the elasticsearch objects
- [x] validate sort params
- [x] update to UI that utilizes sorting
I recently learned you can do this sort of declaration to avoid the two lines on one, via:

```
UnsortableFieldError = Class.new(RuntimeError)
```