Add enumeration to document EKF SolutionStatus

[peterbarker]

this isn't used for anything but documenting the solution status field, which can be used in the Wiki and in various log analysis tools

[peterbarker]

2024-10-16 15:42:31.151: XKF4
    TimeUS: 1848065904 µs
    C: 2 instance
    SV: 0.1 
    SP: 0.02 
    SH: 0.05 
    SM: 0.04 
    SVT: 0.04 
    errRP: 0.006802107207477093 
    OFN: 5.542076110839844 m
    OFE: -0.1966709941625595 m
    FS: 0 
    TS: 32 
    SS: 107327 
        ATTITUDE (attitude estimate valid)
        HORIZ_VEL (horizontal velocity estimate valid)
        VERT_VEL (vertical velocity estimate valid)
        HORIZ_POS_REL (relative horizontal position estimate valid)
        VERT_POS_REL (absolute horizontal position estimate valid)
        VERT_POS (vertical position estimate valid)
      ! TERRAIN_ALT (terrain height estimate valid)
      ! CONST_POS_MODE (in constant position mode)
        PRED_HORIZ_POS_ABS (expected good relative horizontal position estimate - used before takeoff)
        PRED_HORIZ_POS_ABS (expected good absolute horizontal position estimate - used before takeoff)
      ! TAKEOFF_DETECTED (optical flow takeoff has been detected)
      ! TAKEOFF_EXPECTED (compensating for baro errors during takeoff)
      ! TOUCHDOWN_EXPECTED (compensating for baro errors during touchdown)
        USING_GPS (using GPS position)
      ! GPS_GLITCHING (GPS glitching is affecting navigation accuracy)
        GPS_QUALITY_GOOD (can use GPS for navigation)
        INITALIZED (has ever been healthy)
      ! REJECTING_AIRSPEED (rejecting airspeed data)
      ! DEAD_RECKONING (dead reckoning (e.g. no position or velocity source))
    GPS: 0 
    PI: 2