This commit prepares the `winch` crate for updating `wasm-tools`,
notably changing a bit about how the visitation of operators works. This
moves the function body and wasm validator out of the `CodeGen`
structure and into parameters threaded into the emission of the actual
function.
Additionally the `VisitOperator` implementation was updated to remove
the explicit calls to the validator, favoring instead a macro-generated
solution to guarantee that all validation happens before any translation
proceeds. This means that the `VisitOperator for CodeGen` impl is now
infallible and the various methods have been inlined into the trait
methods as well as removing the `Result<_>`.
Finally this commit updates translation to call `validator.finish(..)`
which is required to perform the final validation steps of the function
body.
3b9668558f