build: add wasm support - #36

@dfrankland can you split the codegen into a seperate commit just so that its easier to review?

Also gratzie!

I've rebased and moved file changes to crates/libghostty-vt-sys/src/bindings.rs and the new crates/libghostty-vt-sys/src/bindings_wasm.rs to their own commit.

Happy to make any other changes you'd like 👍

Sorry about the delay in reviewing this @dfrankland . Aiming to get back to this during this week.

cc @pluiedev

I attempted to address the comments added, and I've rebased this PR on top of master.

@pluiedev I'll merge this in after landing your PR's.

I've rebased once more onto master and checked everything passed on linux x86_64 + mac aarch64

Pending CI/CD. It failed previously

I can't really run and adjust CI to ensure everything works, but I believe there's an issue with the Nix develop shell hook unsetting env vars needed on CI for Zig to build. I made a small work around to keep those env vars based on the CI env var being present.

I'm not really sure why local Nix develop shells would want to use the system SDK rather than the one provided by the Nix flake, so it's hard for me to tell if this is a change you'd want to accept.

Rebased on to master to keep up with bindings.rs updates

@dfrankland you have done more than enough.
I just need to find a window where i can sit down, fix shit, and get this over the finish line. I'll handle the rest, appreciate the effort you've put in so far!