figure out good paradigm for handling for mr-model's color

[hanbollar]

          > ## Notes

• there's a discrepancy in MaterialStyleSystem for background color and css understanding of what a model's color is since a model will also have a background - this will need to be figured out in a new issue/pr since it's more 'what would a user try to do in these different cases' research type question first

• background color is being used for MRDivEntity's background (ie mr-model's background plane)
• color is already being used for text coloring on that div
• what to use for the model's actual coloring?

Originally posted by @hanbollar in #570 (comment)

[hanbollar]

@lobau proposed this on discord:

mr-model {
  color: #000 /* the text color */
  background-color: #fff /* the backgroud color */
  material-color: #f90 /* the three js material color? */
}

[hanbollar]

noting other thoughts from discussion this morning:

@michaelthatsit also proposed two alternative options:

• sticking more with data-attributes for this since it's an off-case and we might not want to introduce a new css-specific variable since we dont want to add to many 'new' css features longterm, just add existing
  • pro: not adding a new css feature
  • con: not leaning into the use of the style-sheet for a style feature
• overloading the color css attribute even if that's specifically for text (so if mr-text is a subtag, it would use that same coloring)
  • pro: handles the edge case of not introducing a new css property, but still getting one
  • con: really does not follow css paradigm as color is usually 100% for text only

and other things we talked about are pro/cons of this overall based on css proposal in above comments and prev ones as well

following this - going to sit on this and revisit in next version to see which makes most sense long term from a usabilty && maintainability perspective before we implement