arrow

ARROW-13466: [R] make installation fail if Arrow C++ dependencies cannot be installed

The first commit should fail on the "without-arrow" CI build. I'll then add an env var so we can still test that setup.

Closes #10950 from nealrichardson/fail-without-libarrow

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Neal Richardson <neal.p.richardson@gmail.com>