Support for Juniper System GPS receivers in iOS

Juniper System GPS receivers are registered in Apple's MFi program.
Such devices can be connected directly via Apple External Accessories API, see: https://developer.apple.com/library/archive/featuredarticles/ExternalAccessoryPT/Introduction/Introduction.html#//apple_ref/doc/uid/TP40009502

If we manage to connect a GPS receiver directly in Mergin Maps, we will be able to receive NMEA sentences directly from the device. Thanks to that we will be able to show advanced GPS information like HDOP, number of satellites, accuracy and more.

See https://junipersys.com/support/article/14709
See https://junipersys.com/support/article/14650
How to become an official Geode supported app: https://junipersys.com/data/support/documentation/geode/connecting-ios-apps-to-geode.pdf

There might be other GPS receiver manufacturers registered in MFi program as well, we might want to do a little research.

Start by reviewing Apple's External Accessories API and the Juniper Geode documentation linked in the issue. Identify the iOS entry point for connecting external accessories and receiving NMEA sentences, then determine how GPS details such as HDOP, satellite count, and accuracy are exposed. Done means Juniper receivers work in Mergin Maps and the scope of support for other MFi receivers is documented.