move CSS and stylesheets out of DOM

[jderochervlk]

Moves css and stylesheet related types out of DOM.

[tsnobip]

@jderochervlk what's the motivation here? Make Base feature lighter and move it to DOM feature? IMO DOM feature (not DOM.res) is already quite big in itself plus you have to take into account its feature dependencies, it's likely around 90% of the whole project right now.

[jderochervlk]

@jderochervlk what's the motivation here? Make Base feature lighter and move it to DOM feature? IMO DOM feature (not DOM.res) is already quite big in itself plus you have to take into account its feature dependencies, it's likely around 90% of the whole project right now.

I'm trying to slim down DOM.res as much as possible, you can see a larger lift in that direction on this PR: #287

DOM.res should eventually become DOM the feature, which should be lightweight. Not every project will need style sheet and CSS, so by moving this out you make using it opt in.