Adds variations in GPS coordinate OSD element display:
1. Fractional degrees with 7 digits (default) - 000.0000000
2. Fractional degrees with 4 digits - 000.0000
3. Degrees, minutes, seconds - 000^00'00.0"E
4. Open Location Code (sometimed called Google Plus Code) - 23ABC4R8+M37
Uses Open Location Code library from:
https://github.com/google/open-location-code
Added support for `STATE(GPS_FIX_EVER)` to differentiate from having a fix now (`STATE(GPS_FIX)`) vs. ever having a fix.
Logic change to only display coordinates from the GPS module once a fix has been initially established. This prevents displaying interim coordinates supplied by the GPS while the fix is still being establised as these coordinates can be inaccurate by hundreds of miles. Once a fix is established initially then the coordinates will continue to be displayed even if the fix is lost or degrades in quality.
Add logic to "blink" the coordinates if the 3D fix is lost after initially being established. Alerts the user that the coordinate display may be inaccurate or no longer being updated. We want to keep the coordinates displayed to aid recovery if the user loses the fix (like crashing upside down).
Replace GPS defines `LAT` and `LON` used throughout the code with the enumeration:
```
typedef enum {
GPS_LATITUDE,
GPS_LONGITUDE
} gpsCoordinateType_e;
```
The Open Location Code option is bounded with `USE_GPS_PLUS_CODE` to allow it to be excluded if needed for targets with limited flash space. It currently fits for F411 but we may have to remove it in the future.
Bruce Luckcuck