testing/kstars: new aport

This packages kstars, and also some kstar dependencies (e.g. indilib, and stellarsolver) that are useful on their own as well.

Note about indi-3rdparty: This project includes a bunch of different drivers, but I've only built the gphoto2 driver because that's all I currently need. I tried including some others (e.g. libcamera) but they failed for various reasons and I didn't care to debug that right now, so my plan is to build/package additional drivers on demand in the future.