Runtime Implementation Supporting the Sync ABI

[jeremyg484]

The runtime module is built out to what is believed to be a functionally correct implementation for any component that is using the sync ABI. This is essentially equivalent to the level of internal runtime support needed to support WASIp2. Work on host-side WASIp2 implementation (and the supporting compile-time wit-bindgen infrastructure and additional user-facing API surface that would be necessary) is left to be the next major phase of work.

This implementation passes all of the tests from the Component Model spec repo (save for a handful of documented exceptions) that do not require async support.

The support for the spec test suite is enhanced to more rigorously enforce the assertions therein, fully comparing messages of expected error cases and exercising the full parsing, instantiation, and function invocation pipeline wherever required by the tests.

A Validator interface is introduced to the Parser module, and an implementation is required to be provided by default. The tests provide an implementation that uses the ComponentValidate wasm-tools class to validate the binary form of a component before parsing. Additional validations that must be applied after parsing in order to meet certain expectations of the spec test suite are provided as a default method in the interface.

The ComponentLinker is the main API surface for instantiating components. It processes the parsed component's sections in order and wires everything together, performing the necessary lifting and lowering as specified by the Canonical ABI. It works under the assumption that a component binary has already been validated by something such as wasm-tools. It performs extensive type checking of imports at the host boundary, enforcing the inter-component contracts that cannot be validated by wasm-tools' view of a single component binary.

To achieve type-checking more efficiently, sort indices in the parsed AST are resolved as they are encountered by the ComponentLinker, relying upon the spec rule that an index always references a preceding definition. This results in reduced complexity in the canonical-abi module as well, and its API contracts have been refactored to work with these fully resolved types.

The relationship between a ComponentInstance and its ComponentStore is evolved from the original skeleton runtime implementation. A ComponentInstance now manages its own state and index spaces rather than delegating to the store. There is now a 1:N relationship between the ComponentStore and ComponentInstances. This aligns more with how the Store is described in the specification and matches the approach that Wasmtime has taken.

[jeremyg484]

@andreaTP My apologies in advance for the large size of this PR. It was going to be unavoidably large just from the runtime build-out, but then as I was revising and implementing import type checking, some refactoring to canonical-abi also proved necessary. No rush to review, I'm going to be pretty swamped with other work for the remainder of this week.