Standardising line heights throughout components to match spacing

[bia]

Builds upon #424, line heights of fonts are sporadically set in some but not most components which have text.

cc @miklosp

After quite some research, it seems best to implement a line height relative to font size of 1.618 throughout the entire app instead. @fbarl what is the best way to override this everywhere?

[fbarl]

Sounds good to me!

According to the article, it should be enough to add that one line of CSS somewhere at the top of our app (probably in service-ui rather than here) and then make sure we remove all the rest of line-heights from the styles. We could probably even add line-height to the stylelint blacklist to forbid the overrides: https://stylelint.io/user-guide/rules/property-blacklist/