This commit adds support for import assertions.
Major changes include:
- removal of "ResolveCallback" (deprecated in V8)
in favor of "ModuleResolveCallback"
- removal of "HostImportModuleDynamicallyCallback" (deprecated in V8)
in favor of "HostImportModuleDynamicallyWithImportAssertionsCallback"
The blanket `std:#️⃣:Hash` impl for instances of `v8::Data` invokes
`v8::internal::Object::GetHash()` but that crashes for `v8::Module`
objects. Use a custom impl that calls `v8::Module::get_identity_hash()`.
Fixes the following runtime assertion:
# Fatal error in ../../../v8/src/objects/objects-inl.h, line 1043
# Debug check failed: object.IsJSReceiver().
Refs: https://github.com/denoland/deno/pull/8354#discussion_r522157813
* Merged all handle type implementations into one file ('handle.h').
* Made it so that `Global` handles cannot be empty.
* Renamed the `AsHandle` trait to `Handle`, and made it more generally
useful.
* Simplified how `PartialEq` is implemented for V8 heap objects and/or
the `Local`/`Global` handles that reference them.
In v8.h, not all heap object classes actually derive from `v8::Data`,
but this seems to be a mistake, because this hierarchy does definitely
exists in V8's internal source code.
