Add composer.json

Problem/Motivation

Automated tests do not run properly due to the lack of a composer.json file. For example, see 📌 Automated Drupal 11 compatibility fixes for bartik Needs review .

Also, a 1.0.x release node should be created. The master branch should be renamed to 7.x-1.x.

Proposed resolution

Add a composer.json file.

Remaining tasks

Implement.

User interface changes

None.

API changes

None.

Data model changes

None.