[helpers TS conversion] async functions/generators

[SukkaW]

Q	A
Fixed Issues?	Part of #16500
Patch: Bug Fix?	No
Major: Breaking Change?	No
Minor: New Feature?	No
Tests Added + Pass?	Yes
Documentation PR Link
Any Dependency Changes?	No
License	MIT

Migrate all async functions/generators related Babel helpers to TypeScript with reasonable types (and a huge amount of TypeScript exercise~).

The PR also introduces a small change to the helper building script.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/57072

[liuxingbaoyu]

Thank you very much for the extremely high quality PR!
Unfortunately we generally assume that helpers need to support running before execution (i.e. before the global var is initialized), which is used when circular references are used, so we may need to keep the original form here.
❤️

[nicolo-ribaudo]

Merged, you can rebase

[SukkaW]

@nicolo-ribaudo Sorry for the late response. I am a bit busy recently. I am going to continue working on the PR ASAP.

[ehoogeveen-medweb]

By the way, Ron Buckton has been doing a bunch of work recently to improve the types of iterators in TypeScript itself recently: microsoft/TypeScript#58243 (and related PRs)

I don't know to what extent the babel helper types should equal the standard library types or if there are any lessons that can be learned from that work that would be applicable here, but I wanted to mention it given the timing :)

[SukkaW]

@nicolo-ribaudo It appears the new helper generation script is not included in the babel-old-version, causing the CI to fail.

Is it a blocking factor?

[nicolo-ribaudo]

We should get that CI job green, but I can take a look at it tomorrow