Initial component model and GC support in fused adapters

[fitzgen]

This lays down the initial infrastructure for support for GC in our fused adapters for the component model. We keep track of whether each lifted/lowered function wants args/results as GC values or in linear memory. We additionally plumb through the core function types of the functions being lifted and lowered for (eventual) use with GC adapters.

Ultimately, this commit is enough to fuse together lifted and lowered functions where one or both are using the GC variant of the canonical ABI. Attempting to actually pass arguments will hit todo!()s. The work of implementing those todo!()s is left to future commits.

[fitzgen]

Making it so that the options always have a core type was actually really nice, and a bunch of initializers that previously had options and a core type no longer need a separate core type.

Anyways, I think this is ready for another round of review.

[github-actions[bot]]

Subscribe to Label Action

cc @fitzgen

This issue or pull request has been labeled: "fuzzing", "wasmtime:api"

Thus the following users have been cc'd because of the following labels:

• fitzgen: fuzzing

To subscribe or unsubscribe from this label, edit the .github/subscribe-to-label.json configuration file.

Learn more.