Also stop supporting `var` with initializer inside `for`.
Resolves TODO in `handle_variable.cpp`
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Co-authored-by: Richard Smith <richard@metafoo.co.uk>
I was suggesting this because `FloatingPoint` is pretty long. `int` and
`float` should be familiar abbreviations. `unsigned` should be familiar
to developers too, but `UnsignedInt` still feels usefully clearer for
the additional chars.