[FEATURE REQUEST] Allow importing from, and exporting as, alternative applications' configuration formats.

[RokeJulianLockhart]

Preflight Checklist

• I have read and I agree to follow the support disclaimer.
• I am sure that my feature request has nothing to with third party extensions.
• I am using the latest available Paperback version (currently 0.8).
• I have searched the issue tracker for a feature request that matches the one I want to file, without success.

What type of Apple device is the feature request for?

All device types

Describe the feature

I want to be able to export configurations to, and import configurations from, alternative, well-maintained clients, that exist for alternative OSes.

Feature Motivation

• I already utilise alternative clients, but want to trial PaperBack. Consequently, I want to be able to import data from alternative clients.

• Because PaperBack does not support non-Darwin-based OSes, when not utilising them, I want to be able to export my data in a format that alternative OSes' clients are able to consume.

Anything Else?

Most of these clients exist for AOSP. Mihon is an example. issues/825#issuecomment-4119196422 elaborates.