[R] Compression codec should take a "level"

[asfimport]

See ARROW-6216 for the C++ side.

Reporter: Neal Richardson / @nealrichardson
Assignee: Romain Francois / @romainfrancois

PRs and other links:

• GitHub Pull Request #5450

_{Note: This issue was originally created as ARROW-6533. Please see the migration documentation for further details.}

[asfimport]

Neal Richardson / @nealrichardson:
Issue resolved by pull request 5450
#5450