Allow top-level await in console.require scripts

[haltman-at]

Issue

This issue is a follow-on to #4174, which is in turn a follow-on to #2472.

Much of what one would want to do in a console startup script would not only involve contract abstractions, but would involve performing asychronous operations with them and awaiting the results. So, we should allow top-level await in console startup scripts.

See also: #3349, #1546. It may be necessary to address those first, or we may want to address these all together.

Environment

• Truffle version (truffle version): 5.4.0