Fix color selection discrepancy on selecting a color with native dialog in macOS

We used a dumbConverterInstance to set the new coloe in the DualColorButton, this caused drift in colorspaces different than RGB-8bit system built-in. Now we use previous KoColor colorspace information to convert to QColor.

Test Plan

All color selectors make QColorDialog on macOs report the same color.

Formalities Checklist

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