Make carbon styles scoped

[jarekdanielak]

Is your feature request related to a problem? Please describe.

Carbon styles that are used here seem to be quite invasive and cause issues in Desktop Modeler:

• Literal expression editor styles broken camunda/camunda-modeler#4550
• Welcome tab changes font size camunda/camunda-modeler#4555

Describe the solution you'd like

Unless we want to continue adding explicit styles everywhere else, we should think of a way to encapsulate carbon styles in the scope where they are used.

@marstamm has found an article that shows a somehow hacky way to do it: https://tinytip.co/tips/scss-load-css/