Async support + various fixes

[joeycumines-swyftx]

I was evaluating your implementation, and made these changes while doing so.

I'd say I'm happy with the concept, and fairly happy with the API it provides. IMO, the biggest issue is that w/o async support this package has only limited usefulness.

Features:

• Added AsyncContextManager, as a superset of ContextManager (with the same two methods / behavior)
• Refactored With to support return values from the body
• Added AsyncWith Same thing, but async
• Added AsyncUse and Use (context manager to generator, as a more-limited alternative to With)
• Refactored closing to (also) support async context managers

Fixes / tweaks:

• Only suppress if exit actually returned true, not just truthy
• Stripped console.log calls (immediate deal-breaker, as someone evaluating a package)
• Identify the error case (within implementations of / that call exit) via arguments.length (undefined can be thrown)
• Added tsconfig, linting etc

Type fixes / tweaks:

• Made this package build (with our TS config), by addressing the incorrect assumption that only Error values will ever be thrown
• Fixed/tweaked various signatures (I made an effort to make them all compatible, but I have no reliable way to verify this)
• Deprecated the interfaces that I could not see any value in exporting
• Deleted the unexported body type (that was used in one place)

[Mcsavvy]

Nice fixing

[Mcsavvy]

I was working on separate branches for ts and js