It is possible for two `WasmSubType`s to be equal to each other, as far as
`derive(PartialEq)` is concerned, but still different from each other if they
are in different rec groups or even if they are at different indices within the
same rec group. The assertion mistakenly did not permit either of these,
however.

Fixes bytecodealliance#9714

…dule,Component}`s

Rather than canonicalizing them on demand in functions like
`{Func,Global,Table}Type::from_wasmtime` and other places. Instead, we do it in
one place, up front, so that it is very unlikely we miss anything. Doing this
involves changing some things from `ModuleInternedTypeIndex`es to
`EngineOrModuleTypeIndex`es in `wasmtime_environ`, which means that a bunch of
uses of those things need to unwrap the appropriate kind of type index at usage
sites (e.g. compilation uses will unwrap `ModuleInternedTypeIndex`es, runtime
uses usage will unwrap `VMSharedTypeIndex`es). And it additionally required
implementing the `TypeTrace` trait for a handful of things to unlock the
provided `canonicalize_for_runtime_usage` trait method for those things.

All this machinery is required to avoid an assertion failure in the regression
test introduced in the previous commit, which was triggered because we were
failing to canonicalize type indices inside `ExternType`s for runtime usage on
some code paths. We shouldn't have to play that kind of whack-a-mole in the
future, thanks to this new approach.