Set color for each guide, for visual grouping

Operating System: All

Description of the feature

Allow to set the color of each guide, or to a group of guides, for visual grouping.

Use cases

For page layout, I want to create guides at 25/50/75% and 33/66%, as well as at 0/100%[*]. So as there are many guides, it becomes confusing.

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[*] Because when resizing a layer for example, we don't see the borders of the image (OK, workaround because I disabled the "show boundaries" because it's annoying).