Responsive image field formatter list should be sorted by label, not machine name

Problem/Motivation

Currently when configuring a responsive image format for a field, the list of responsive styles are sorted by machine name, not the style label. This can be confusing if the style labels are set so they display in a particular order, just as to map to a size scale.

Also, since the machine name is going to be removed from the styles table list with: #2988905: Remove machine name data from Responsive image styles table this will make the formatter list appear unsorted altogether.

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet