Use Tabs over spaces in formats and repo as a whole

[jorenbroekema]

Instead of using , we should use \t character so the amount of indentation becomes configurable by the user.

It also has accessibility implications, customizing indentation width is helpful for visually impaired folks who have trouble with distinguishing indentation levels e.g. when it's only 2 spaces wide. Also, for braille users (blind folks), a tab character takes up way less space than let's say 4 space characters, making it much easier to work with.

We started experimenting with it here: #1344 , new formats should start using it, this issue is about changing the old formats as well as a breaking change for v5