Theme-builder for smaller screens

[Febakke]

Right now we are breaking WCAG guidelines with our... special handling of smaller screen sizes in our theme builder.

I got a feeling most people that are creating and building colorscales for code and Figma are using a bigger screen size. But if you are browsing our page with a phone it is a little weird that it totally fails when entering the theme builder.

My suggestion is to make a alternative view for smaller screens that only show some important elements for browsing.

[mrosvik]

Suggestion from @Barsnes ; Use dialog on mobile to open the content from sidebar

[mrosvik]

@Febakke and @Thunear will create a suggestion

[Barsnes]

In PR #3294, the themebuilder was made usable for smaller screens. No work was done to check if the userflow is any good, it was just to fix big issues.