Consider limit codebase max line length to 80/100 via default formatting

* Limit the line length is a usual convention that helps to read the codebase (see serokell haskell style guide f.e: https://github.com/serokell/style/blob/master/haskell.md#line-length, but many other style guides recommend it):

> You should keep maximum line length below 80 characters. If necessary, you may use up to 100 characters, although this is discouraged. You should wrap imports at 100 characters.

It would suppose reach a consensus and start to progresively apply it in dedicated pr's, trying to dont disturb existing work in progress. I hope stylish-haskell will support it.

//cc @Ailrun, as you have worked fantastically in the formatting of the codebase