[R] Implement S3 file-system interface in R

[asfimport]

Reporter: Neal Richardson / @nealrichardson
Assignee: Neal Richardson / @nealrichardson

Related issues:

• [R] Add AWS SDK to system dependencies for macOS and Windows (depends upon)
• [R] Add bindings for filesystem API (depends upon)

PRs and other links:

• GitHub Pull Request #6901

_{Note: This issue was originally created as ARROW-6439. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
aws-sdk-cpp isn't going to be available on Windows (cf. r-windows/rtools-packages#37), so we'll need to make sure that this feature is flagged based on whether the C++ library has been built with ARROW_S3 on.

[asfimport]

Neal Richardson / @nealrichardson:
This is ready to start now.

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 6901
#6901