SAS pipeline: implement a 'quality flag'

[FredSchuller]

We need to add a quality flag to the output of the SAS pipeline, so that the user can assess whether the aspect solution is reliable or not. This requires an additional column in the AUX fits file, which should be read in by the imaging pipeline so that a warning can be issued to the user. If the quality is bad, the pipeline could use the SolO pointing from spice kernel instead.

This flag can encode several quality indicators:

• sun distance above 0.8 AU (always bad)
• sun distance between 0.75 and 0.8 AU (not good, but may be usable)
• any other indication of doubtful results?

[FredSchuller]

@nicHoch
Here is a more detailed description of what is needed.
The SAS processing pipeline should generate a 'quality flag' that indicates how reliable the aspect solution is, for each measurement. This can be encoded in a numerical value (short integer), which reflects the degree of badness as follows:

• 0 = no problem
• 1 = SAS solution suspicious (e.g. during strong off-pointing, or if rapidly changing)
• 2 = SAS solution very uncertain (e.g. when 0.8 > d_Sun > 0.7 AU)
• 3 = SAS solution not usable because d_Sun > 0.8 AU

This number has to be written in the AUX file (a new column is needed), so that the imaging pipeline on the GSW side can read it and decide on how to deal with the pointing.

[FredSchuller]

Additional reasons for bad quality:

• solar image radius outside of range covered by simulated data
• aspect solution found on the edge of the parameter space in the simu. data
• solution found well beyond solar limb