Retrieve the list of available instances automatically
## :memo: Description
According to https://community.openstreetmap.org/t/deutscher-panoramax-server/111586/73, there exist https://api.panoramax.xyz/api/instances which returns a list of available panoramax instances.
Adopting that JSON API instead of having instances hardcoded in [InstanceEntity.kt](https://gitlab.com/ravenfeld/baba/-/blob/main/lib-login/impl/src/commonMain/kotlin/com/ravenfeld/panoramax/baba/lib/login/impl/model/InstanceEntity.kt) should allow for automatic pick up of new instances as they become available, and reduce project-specific translation efforts for Baba!
## :dart: Objectives
- have list of Panoramax instances update automatically as they become available (instead of having to make Baba MR and waiting for new release)
- reduce duplicated translation effort
## :camera: Design
## :link: Dependencies
## :closed_book: Documentation
issue