List alternative modules on the module page

Problem/Motivation

The following modules should be listed as alternatives on the module page:

• https://www.drupal.org/project/theme_change →
• https://www.drupal.org/project/switch_theme →

For Drupal 7 https://www.drupal.org/project/themekey → might be worth mentioning?

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes