Option to configure RoPieee via config file on sdcard

Hey @spockfish,

Rather than necro posting on various threads figured I’d start a new one. I have a few different hat’s for various needs but all are on Pi 3 A+'s (no ethernet port), it’s generally a pain to bridge them to a wired network via a dongle configure them then replace them in their cases and off into their location. In another post you mentioned setting up an Access Point if they are not connected to the network, is there a simple middle ground to providing a way to configure wifi via a flash but pre-boot sdcard, perhaps some basic configuration from /boot/config.txt or /boot/ropieee.txt with simple k/v options that can be parsed and added to the configuration file on first boot.

I’m happy to do some of the work and send a PR to support this but it seems the repo that houses this portion of the code is in a private bitbucket.