catphan results: add low_contrast result (pass/no pass) in default results

[AlainSottiaux]

(V2.3.1) Catphan, results() Number of low contrast region "seen" is shown, but test against tolerance (pass/no pass) is not. This value is already available in CTP515 properties (overall_passed), and so could already be manually added to any analysis output.

[jrkerns]

Indeed. You are free to make your own custom .results() method that contains the information you'd like.