WIP: unify the RAK targets into one firmware (#1350)

* First steps to unify GPS Lib for RAK 1910 and RAK 12500

* Technicalities. Out with the old and build the new.

* Adapt Matrix

* We use 0.4.5 now

* While we're at it, yank the RAK815, it's EOL

* Satisfy CI - for now

* - yank UBX library, talk to GPS chip with NMEA only.
- more autodetect going on, this time for the Eink Display.

TODO: actually do something with the scan findings.

* i swear this works on windows! :-)

* these are only there to make CI happy

* don't update eink display if not detected.

* Replace Oberon Crypt Library with modified Adafruit Library. This elimintaes the need for the sdk-nfxlib submodule.

* - Revert auto screen selection (incomplete)
- Revert nrF crypto engine (needs more work)
- add separate defines for not-auto-selecting screen lib.

* Define 2 new variants for RAK - with or without epaper

* Update variants

Co-authored-by: Sacha Weatherstone <sachaw100@hotmail.com>
Co-authored-by: Ben Meadors <thebentern@tuta.io>

src/gps/GPS.h

@@ -40,9 +40,6 @@ class GPS : private concurrency::OSThread
     /** If !NULL we will use this serial port to construct our GPS */
     static HardwareSerial *_serial_gps;
 
-    /** If !0 we will attempt to connect to the GPS over I2C */
-    static uint8_t i2cAddress;
-
     Position p = Position_init_default;
 
     GPS() : concurrency::OSThread("GPS") {}