support motor intialization status tracking

[runger1101001]

Simple tracking of the motor initialisation status.

This allows an external observer to know whether the motor is uninitialised, uncalibrated, currently calibrating, etc...

The following stati are tracked:

enum FOCMotorStatus : uint8_t {
  motor_uninitialized = 0x00,     //!< Motor is not yet initialized
  motor_initializing  = 0x01,     //!< Motor intiialization is in progress
  motor_uncalibrated  = 0x02,     //!< Motor is initialized, but not calibrated (open loop possible)
  motor_calibrating   = 0x03,     //!< Motor calibration in progress
  motor_ready         = 0x04,     //!< Motor is initialized and calibrated (closed loop possible)
  motor_error         = 0x08,     //!< Motor is in error state (recoverable, e.g. overcurrent protection active)
  motor_calib_failed  = 0x0E,     //!< Motor calibration failed (possibly recoverable)
  motor_init_failed   = 0x0F,     //!< Motor initialization failed (not recoverable)
};

Only the initialisation is affected, the status is not used by the rest of the code.

I have so far tested on STM32.

[runger1101001]

Ok, lets merge to dev since there were no objections :-)