Report skip reason

[richardmillson]

Is your feature request related to a problem? Please describe.
It would be nice to report the reason files were skipped in the message returned to users.

Describe the solution you'd like
The skip category is available in ModelScanSkipped as self.category and could be added to the string returned at

modelscan/modelscan/skip.py

Line 44 in abc4b15

return f"The following file {self.source} was skipped during a {self.scan_name} scan: \n{self.message}"

Describe alternatives you've considered
This would be the most minimal change to accomplish this.

Additional context
This would partially resolve, or at least provide information desired in, issues #290 , #250 , #218 .