Add *.wast support for invoking components (#4526)

This commit builds on bytecodealliance/wasm-tools#690 to add support to
testing of the component model to execute functions when running
`*.wast` files. This support is all built on #4442 as functions are
invoked through a "dynamic" API. Right now the testing and integration
is fairly crude but I'm hoping that we can try to improve it over time
as necessary. For now this should provide a hopefully more convenient
syntax for unit tests and the like.

crates/wast/src/lib.rs

@@ -21,6 +21,9 @@
     )
 )]
 
+#[cfg(feature = "component-model")]
+mod component;
+mod core;
 mod spectest;
 mod wast;