fix(provisioning_api): Fix AppInfo schema for OpenAPI

[provokateurin]

Summary

There are a few mistakes in the current schema (e.g. multiple language support for name, description and summary). Instead of trying to fix those problems I opted for generalizing the whole schema as the provided type information was mostly useless anyway (values typed as ?mixed). This could have also led to problems in case the XSD was updated and this schema wasn't, so this avoids it. The real problem is that the AppStore data is simply passed through without any checking for any structure, but that can't be fixed easily.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[provokateurin]

/backport to stable28

[come-nc]

🤷