Reported diagnostics act as if tabs are expanded to 8 spaces

[lePerdu]

When using tabs for indentation, diagnostics report incorrect columns, acting like the tabs are 8 spaces. I wrote a (failing) test case for this here: https://github.com/lePerdu/java-language-server/blob/test/expands-tabs/src/test/java/org/javacs/WarningsTest.java#L38

Workaround by replacing tabs with single spaces here (this probably breaks other things like formatting, but is what I'm using in the meantime): https://github.com/lePerdu/java-language-server/tree/workaround/expand-tabs