Async main as the default for none @main defined scripting cases

It is probably a niche case that I wrote Swift code that doesn't really have a @main struct / function, but rely on implicit main for executions (much like using it as a scripting language). Right now, this case seems wrapped as synchronous main.

After reading SE-0323: Asynchronous Main Semantics - #10 by Douglas_Gregor, it doesn't seem to me there is a roadblock for this case moving to async, it is more like an oversight? If we just treat this case as async main, and run up until the first suspension point (if any), everything should work.

Let me know what do you think, or am I missing any new proposals.

IIUC, this is already an accepted part of Swift 5.7. Here is the proposal: SE-0343.

Thank you! I should track these more closely.