Add validaton for 64bit component model

[michael-weigelt]

This is a checklist issue to track the progress of the implementation side of this 🐘 spec PR.

The following is a list of subfeatures that are not or only loosely related and can be worked on independently. Validating a 64bit component model module will (in general) only really work once they are all done, but since the feature is behind a feature flag, it is ok for the feature to be in an incomplete state.

• Feature flag #2496
• resource rep #2496
• realloc
• context.{get, set}
• waitable-set.{wait, poll}
• stream.{read, write}
• future.{read, write}
• thread.new-indirect
• thread.spawn-ref
• thread.spawn-indirect
• error-context.new
• error-context.debug-message