Add support for multiple custom sort criteria labels

Problem/Motivation

You can set custom labels for ascending sort and descending sort under Advanced > Exposed form > Exposed form style Settings by filling out Label for ascending sort and Label for descending sort, which works well.

But these labels are used for all sort criteria, which is limiting.

Steps to reproduce

Want to have several different sort labels, but only be allowed to set one universally used for all sort criteria.

Proposed resolution

It would be nice if you could set a label for ascending and descending sort for each sort criteria, for example "highest - lowest" for a rating field sort, while also having and "ascending - descending" for a name field.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet