* Import Wasmtime support from the `wit-bindgen` repo
This commit imports the `wit-bindgen-gen-host-wasmtime-rust` crate from
the `wit-bindgen` repository into the upstream Wasmtime repository. I've
chosen to not import the full history here since the crate is relatively
small and doesn't have a ton of complexity. While the history of the
crate is quite long the current iteration of the crate's history is
relatively short so there's not a ton of import there anyway. The
thinking is that this can now continue to evolve in-tree.
* Refactor `wasmtime-component-macro` a bit
Make room for a `wit_bindgen` macro to slot in.
* Add initial support for a `bindgen` macro
* Add tests for `wasmtime::component::bindgen!`
* Improve error forgetting `async` feature
* Add end-to-end tests for bindgen
* Add an audit of `unicase`
* Add a license to the test-helpers crate
* Add vet entry for `pulldown-cmark`
* Update publish script with new crate
* Try to fix publish script
* Update audits
* Update lock file
