feat(firestore): async snippets

[rafilong]

Add snippets for new async Firestore interface. Snippets are ported from firestore/cloud-client to firestore/cloud-async-client.

[rafilong]

Force push to overwrite history and make review easier. 6fb670d directly copies sync snippets to async directory, and 495ae79 converts to async. Would recommend reviewing the latter for snippets*.py.

[rafilong]

Question: are annotations scoped to the repo, project, or file? I assumed the latter, so snippets tags are shared between sync and async.

[BenWhitehead]

This looks great @rafilong!!! Thanks for getting all this done.

One thing we need to do is figure out a naming scheme for the async samples so that defsite doesn't union these new samples and the existing ones.

@busunkim96 @crwilcox Do we have a naming schema already defined for async clients and samples?

[crwilcox]

We don't have a pattern yet but I feel like appending async to the region tag makes sense as it would group with the other sample. Still haven't settled on how to display these though. For instance, should they both show under python or do we want a new Python (async) tab similar to how Java has the Android version.

Either way we need to settle on a new region tag. How are the Android ones separated?

[BenWhitehead]

It looks like in Android the java/kotlin separation is handled by the sample registry indirection (though I'm not familiar with how that actually works).

I'm okay with having an _async suffix if that's how we want to do it. Though, I'm not sure of the best way to do this. I know lots of snippets are managed lots of different ways.

[rafilong]

@BenWhitehead @crwilcox would adding an _async suffix as a temporary stopgap so we can merge this in reasonable? It should be a relatively quick fix in the future to implement a better solution, and a suffix seems fairly reasonable.

[BenWhitehead]

Adding the _async suffix SGTM

[rafilong]

@BenWhitehead @crwilcox suffix added!