Non-Latin fonts for the UI

### Describe the problem

Weblate currently bundles *Source Sans* / *Source Code* fonts which cover Latin script only. Any other scripts will fall back to the browser fonts. The assumption is that the user has fonts for the languages they are translating.

This might bring some issues, though:

* The system fonts might not look as good as third-party ones for some scripts.
* Users without these fonts will not see these texts rendered (for example, when looking at translations in other languages than you translate).

### Describe the solution you would like

The solution needs to be decided:

* Should Weblate ship additional fonts? The size of Weblate package could grow considerably when adding a few fonts.
* Which scripts to cover? We probably can't cover all the scripts.
* Weblate already ships Kurinto font which is used when rendering PNG widgets. Maybe we could use this in the UI?

### Describe alternatives you have considered

The current approach works well for most of the time and could be kept.

### Screenshots

_No response_

### Additional context

This issue is to get opinions about this topic. Please share your thoughts.

@Geeyun-JY3 @BoFFire @yarons @meel-hd