Remove [[Construct]] and exoticness from wrapped async functions

[littledan]

I don't think the [[Construct]] behavior of .wrap's output is particularly useful; I'd prefer we prioritize simplicity over copying everything that .bind does. Let's have .wrap output an ordinary function instead of some exotic object kind, again for simplicity. This can be done with CreateBuiltinFunction.

[legendecas]

This can be addressed in #55 as it removes the HOF with AsyncSnapshot. AsyncSnapshot.prototype.run and AsyncLocal.prototype.run merely call the given function.