Inconsistent handling of line endings on Windows vs Linux

Currently 35 tests on Windows fail.

Git converts all line endings of text to CRLF on Windows (default git behavior).
Using the git config `core.autocrlf=false` will fix most of the tests.
Adding a .gitattributes with `* text eol=lf` should work for everyone, although it would hide the underlying issue.

Many errors stem from some incorrect handling in the Lexer, e.g. here:
https://github.com/effekt-lang/effekt/blob/a4c916fa3506db9899bc4387bdba14c8fee3578f/effekt/shared/src/main/scala/effekt/Lexer.scala#L627

Other errors come from string literal comparisons that fail, since the tests only expects '\n'.

As stated, there are a total of 35 tests that are failing and i am willing to share more insights and even fix them, when needed.