Support ES modules

The runtime currently handles commonjs modules - and if an import statement is encountered the application will crash.

The implementation is currently in ModuleInternal.mm

It would be awesome if es modules were supported, since v8 already supports them - we are just missing the implementation for loading them (same-ish logic as for commonjs)

A reduced example for supporting es modules: https://stackoverflow.com/a/52031275/2270725

The gist of it is - we have to call ScriptCompiler::CompileModule on the source

Local<Module> module;
if (!ScriptCompiler::CompileModule(isolate, &source).ToLocal(&module)) {
  // if you have a v8::TryCatch, you should check it here.
  return;
}

Unresolved questions:

• Can the runtime support both types and interop between them?

Start in ModuleInternal.mm by tracing the existing commonjs loading path and compare it with the provided ScriptCompiler::CompileModule example. Investigate how V8 module loading and commonjs interoperation should work. Done means import statements no longer crash and the runtime supports the intended interaction between both module types.