GitHub Actions seems to be hiding colored whitespace, and after lots of
attempts I couldn't find a way to work it around.
So instead I'm using a perl expression to replace trailing spaces with
`·` and tabs with `<TAB>` in the ANSI colored diff output. This ensure
that they're visible, and they are properly colored as expected too.
It was failing due to generated files being referenced in
.NET projects but the files are missing because they are
generated by `godot --generate-mono-glue` or
`build_assemblies.py`.