2489: Implement `format_args` r=flodiebold a=flodiebold
This fixes a huge amount of type mismatches (because every format call was a type mismatch so far); I also hoped to get go to def working within `format!` etc., and the test says it should, but in practice it still doesn't seem to...
Also remove the `len` parameter from `Name::new_inline_ascii`, which I'm assuming was only there because of `const fn` limitations?
cc @edwin0cheng
Co-authored-by: Florian Diebold <flodiebold@gmail.com>
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