This commit fully implements outer aliases of the module linking proposal. Outer aliases can now handle multiple-level-up aliases and now properly also handle closed-over-values of modules that are either imported or defined. The structure of `wasmtime::Module` was altered as part of this commit. It is now a compiled module plus two lists of "upvars", or closed over values used when instantiating the module. One list of upvars is compiled artifacts which are submodules that could be used. Another is module values that are injected via outer aliases. Serialization and such have been updated as appropriate to handle this.
This is the wasmtime-jit crate, which contains JIT-based execution
for wasm, using the wasm ABI defined by wasmtime-environ and the
runtime support provided by wasmtime-runtime.
Most users will want to use the main wasmtime crate instead of using this
crate directly.