Add "Ignore colormask" override option for importer

[HiLordReilo]

As stated in the wiki:

Some materials are supposed to have overlays, but KKBP cannot tell when that’s supposed to happen, so it defaults to enabling overlays.

However, what if user knows there are no materials that have overlays or they just didn't use overlays? In that case it would've been nice to have an option to force "Ignore colormask" to 0 for materials on import to skip fixing white items.