[Feature Request] Add `await` expressions or modify the `functionCall` builder to be able to be set to `await`'ed

[josh-hemphill]

Describe the feature

Everything seems to work just fine modifying modules that use await elsewhere as long as I don't touch await itself, if there's going to be significant complexity in adding a whole new proxied node for await, would it be easier just to make it part of the parts that handle function call expressions, like a flag parameter to prefix it?

I'm happy to help with it, though I'm new to doing AST stuff for the most part.

Additional information

• Would you be willing to help implement this feature?

[antfu]

PR welcome!