adapt data-attributes instead of classes for settings

[nmerget]

    I would expect `class="db-ui-regular"` to be `data-tonality="regular"` (and in the generator files accordingly), adapted by the other attributes like e.g. size (`data-size`), variant (`data-variant`), etc. This seem to have been overlooked in colors, scaling and typography as well.

Originally posted by @mfranzke in #174 (comment)