Otherwise the backends will panic on e.g. `vec4 local = Global;` if the global
isn't used anywere else in the function.

This pretty trivial change unfortunately required a loop to mutably borrow both
builder and manager at the same time, so I had to separate them. Perhaps a
cleaner solution would be to use an object with internal state instead of free
functions.

while, do-while and for loops

i.e. if-else and switch-case

* msl-out: Use io::Write instead of fmt::Write

* msl-out: merge std use

Header blocks were incorrectly overwritten.
format

* [glsl-in] Add initial pre-processor

* [glsl-in] Tweak preprocessor after review

- Add IfState struct
- Use FastHashMap to pre-defines
- Use ok-or() for some errors

* [glsl-in] Remove Option in defines arg

* [clippy] disable match_like_matches_macro for now

* [wgsl-in] Return error instead of panic

* [typifier] Convert panics to return error

Still one panic in clone impl for Resolution,
disabled clippy for that one

* [spv-in] REturn error instead of panic'ing

* [spv-out] Return error instead of panic'ing

* [typifier] Use IncompatibleOperand(s) error

Instead of just Other

* [typifier] Use Expression for op in Error

For IncompatibleOperands

* [typifier] revert last commit

Have single place where advancing to next line