[FontBakeryCheck:opentype/STAT/ital_axis] Relies on GF specific naming to test ital STAT axis in OpenType profile

[benkiel]

(NOTE: Please include the check-id in the issue's title.)

Observed behaviour

Font that is italic, but not named the GF way, is classified as Roman by segment_vf_collection and gives an incorrect warnings for FontBakeryCheck:opentype/STAT/ital_axis

Expected behaviour

Fontbakery uses the is_italic test to classify fonts correctly

Resources and steps needed to reproduce

Any variable font that has an ital axis but doesn't conform to the GF naming of having -Italic[ in the file name will get classified as Roman, and trigger the incorrect report.

[felipesanches]

Thanks for reporting this!

[benkiel]

@felipesanches, the above is a start; feel free to pick it up if you want. I think mostly complete

[felipesanches]

This is similar to #4971