Add UsePreprocessIcon

[adrinewborn]

Enhancements:
Added DrawerUsePreProcessIcon for use colored icon

[orapps44]

Hi, thanks for this great job.
I thinks this new feature may have an interest for users.

However I suggest to change property name UsePreProcessIcons by something like UseColorIcons. This new property should also be set to false by default.

[adrinewborn]

Hi,
In the code the new property is DrawerUseProcessIcons. I just forgot the 's' on MainForm => materialSwitch17.

I fixed the property default True, because in google guideline the icons are monochrome. It's when property is false than the icons are colored and not trasform.