Migrate from @import-rule to @use-rule

[DerPipo]

This is a improvement/refactoring.

Since the @import-rule is deprecated, this PR switches to the @use-rule.

Usage of single parts of bulma (from within sass/scss) was also pretty fiddly, because not every file imported everything it needed, so you had to add the imports on your own where the order of imports also mattered.

Proposed solution

Essentially I did the three following things:

• replace all @imports with the corresponding @uses
  • that required some additional @use statements that were missing
  • and required to use the namespaces
• switch from node-sass to (dart-)sass to be able to use @use
• add stylelint with scss support to make sure that there are no @imports anymore

What I not did (on purpose):

• refactor anything else
• rename anything
• fix any of stylelints other thrown errors
• update any other dependency

Tradeoffs

• to reference variables, you are required to use namespaces, which creates longer names, longer lines and larger files

Testing Done

Projects builds, css output looks good.

Changelog updated?

No.