[R] Implements low-level bindings to Dataset classes

[asfimport]

The following classes should be accessible from R:

• class DataSource

• class DataSourceDiscovery

• class Dataset

• class ScanContext, ScanOptions, ScanTask

• class ScannerBuilder

• class Scanner

  The end result is reading a directory of parquet files as a single stream. One should be able to re-implement ARROW-6950: [C++][Dataset] Add dataset benchmark example #5720 in R. 

  See also https://github.com/apache/arrow/pull/5675/files for another end-to-end example in C++.

Reporter: Francois Saint-Jacques / @fsaintjacques
Assignee: Neal Richardson / @nealrichardson

Related issues:

• [C++] Implements basic Dataset/Scanner/ScannerBuilder (depends upon)

PRs and other links:

• GitHub Pull Request #5454

_{Note: This issue was originally created as ARROW-6340. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 5454
#5454