Conflict with PWA module - show warning

Problem/Motivation

Justl ike responsive favicons, the https://www.drupal.org/project/pwa → module uses a manifest file. If PWA module is enabled besides responsive_favicons module, a warning message should be shown on the Responsive Favicons configuration page, that setting the manifest conflicts with PWA and eventually overwrites the PWA's manifest file, which is hard to find.

We just ran into this issue and it shouldn't happen to others.

Steps to reproduce

1. Use this module in combination with the PWA module
2. Enter or paste the "Favicon tags" from tools like https://realfavicongenerator.net/
3. See the wrong manifest file being used

Proposed resolution

• Add a warning on the configuration form and a notice on the status page, if both modules are enabled.
• Eventually scan the "Favicon tags" field for rel="manifest" and trigger an error, if it's present and PWA module is enabled

Remaining tasks

User interface changes

API changes

Data model changes