[R][Docs] Improve documentation on GCS support

[amoeba]

Describe the bug, including details regarding any error messages, version, and platform.

In the past, Arrow binaries on CRAN had S3 and GCS support by default. This changed a few major versions ago and the current and last few releases have S3 enabled but not GCS. The cloud storage vignette still claims GCS is enabled by default:

Before you start, make sure that your arrow install has support for S3 and/or GCS enabled. For most users this will be true by default, because the Windows and macOS binary packages hosted on CRAN include S3 and GCS support.

(Link)

We should update the docs.

This was originally reported in #44859.

Component(s)

Documentation, R

[assignUser]

Hm I don't quite remember what the reason was to keep gcs of but turn aws on... does it require some tricky dependency on mac that wasn't there? Otherwise turning it on might also be an option ^^

[amoeba]

I'm not sure. @jonkeane do you remember?

[jonkeane]

I think we were just trying to limit the attack surface of CRAN / downloading dependencies to build form source. We certainly could try it (especially on the CRAN mac runners) and see if it works.

[assignUser]

Ah yes, thanks! I'd be either way, as this involves potential nasty-grams I'll leave the choice up to you @jonkeane !

[amoeba]

I think it may be worth trying again, and am happy to try it with the 19.0.0 release though it's not me who gets emails :)

[jonkeane]

I'm fine if we try it on the test infra, and if that goes smoothly possibly get emails. We dealt with the unreleased gcc one just fine 💅

Thanks for taking that on, @amoeba I think it's ok if we try it out for 19.0.0 but wait until 20.0 to merge the PR that really turns it on (unless folks are clamoring for it now, no reason to do an extra patch? I dunno maybe it's not that bad. So either way!)

[amoeba]

That works for me. I'll put this issue in the 20.0.0 milestone and leave it open so we come back to it.