Use ConfigEntityBase::sort() to sort bundles selection choice

Problem/Motivation

When a user is using the IEF comple widget to add an entity, they first have to select a bundle. The list of bundles is sorted alphabetically.

Proposed resolution

Use ConfigEntityBase::sort() as a sort helper to sort the bundles in their preferred way, which may include a weight as well as their label, or something more specific to the bundle entity type.

A slight catch is that not all bundles are backed by config entities, so the code would need to be cautious.

Remaining tasks

User interface changes

API changes

Data model changes