GPS through Gadgetbridge

@HughB @halemmerich To use the gps data from Gadgetbridge, you need to activate it in the settings of the Banglejs device of the Gadgetbrdige as well as in the settings of the "Android" app on the banglejs device. The default values are set to false, so it is not possible to accedentily activate this feature.

Also @halemmerich, another advantage of the gps data from the Gadgetbridge is that we can use the GPS data of the current network (which is not possible on the bangle device). Therefore we can get gps data, even if ther is no connection to any gps sateliets.

All in all a very nice addition to the bangle :) This even makes auto-updating the position for the "My Location" app easy on the battery.

@user148386 thanks for those fixes! Let's hope they get in to Gadgetbridge soon.

Maybe you could also ensure 'long -> lon' in that PR, and then we can also get that fixed at the same time and pull out the change in the PR for BangleApps?

I also noticed there is a comment on https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/3007#issuecomment-760013 - maybe that's why it's not being merged at the moment?

I forgot to add the "long-lon" mapping in that pr and it is already merged.
I created a new one for this change https://codeberg.org/Freeyourgadget/Gadgetbridge/pulls/3019