OCSADV-29: changes to guiding feedback

This PR corresponds to a request from Bryan to improve the guiding feedback.  It also incorporates a few simplifications to the code.  The changes are:

* `AgsAnalysis` is updated to merge the concept of "severity" into "guide quality".  All `AgsAnalysis` options now have a guide quality.  Guide quality can be mapped to Phase 2 checker and QPT warnings and errors.

* The text message associated with an `AgsAnalysis` instance now optionally contains the guide probe name. The message changes depending upon whether or not the name should be included.

* Somewhat simplified calculation of the probe range limit display calculation.

* Moved the feedback label to the selected target itself as requested.  The base position now shows global feedback like "missing OIWFS star" while individual guide stars have specific feedback about magnitudes etc.