Sort config alphabetically if no orderby defined

Problem/Motivation

When exporting configuration some sequences may define an "orderby" attribute, per #2361539: Config export key order is not predictable for sequences, add orderby property to config schema → . If the sequence does not define the "orderby" attribute the export order will be erratic and prone to changes because of unpredictable aspects of the environment, e.g. the specific version of PHP being used.

Steps to reproduce

Proposed resolution

If an orderby definition is not provided in a configuration sequence, default the order to sort alphabetically.

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet