Remove reliance on wit_parser::abi

[alexcrichton]

This commit is the dual of bytecodealliance/wasm-tools#1149 where the code is being moved from the wit-parser crate into this repository where it's mainly developed. This commit adds a wit_bindgen_core::abi module with the same contents as before with small refactorings to avoid inherent methods on Resolve.

Note that this temporarily switches to a git dependency for the wasm-tools family of crates which will be reverted back to a crates.io dependency one they're published.

[guybedford]

Nice! I assume the interface is mostly unchanged in the move?

[alexcrichton]

Yeah this is intended to be a copy/paste, and the only real difference is that instead of self.resolve.foo(...) it's now abi::foo(self.resolve, ...)

[cpetig]

Also a "Nice!" from me. The post-return change in wasm-tools looks worth its own PR as well.

[guybedford]

I was able to update jco to this branch and can confirm it all works as expected.

[peterhuene]

With this now merged, any chance we can do a wasm-tools and wit-bindgen release?

Without one, cargo-component has to generate projects with the same patch.crates-io in it for the wasm-tools dependencies to get things building (currently it references wit-bindgen by git for the resources support), which isn't great.

[alexcrichton]

Sounds good to me! I'll work on the bump PRs later today if no one else has beaten me to it by then.

Wow and I forgot to send this message until I'm ready to do the bumps, sorry about that!