Support for AppStream metainfo files

### Describe the problem

I want to be able to translate the [metainfo](https://www.freedesktop.org/software/appstream/docs/) files of my apps from weblate.

### Solution brainstorm

Implement support for this in the translate library: https://github.com/translate/translate/issues/5261

### Describe alternatives you have considered

The solution I currently use is manually editing the file to include translations, but this is limited to only developers with git knowledge and knowledge of the file format itself.

Other solutions I've seen is using standard tooling to use `gettext` to translate it. Except I'm using fluent to translate the files so I don't want to add one more outdated i18n format to my projects.

### Screenshots

_No response_

### Additional context

Probably depends on

- https://github.com/translate/translate/issues/5261
- https://github.com/WeblateOrg/weblate/issues/11039

This would probably help flathub improve it's app data (most of which is only available in English): https://github.com/flathub-infra/documentation/issues/337