[R] Improve source build experience

[asfimport]

• We should make ARROW_DEPENDENCY_SOURCE=AUTO the default and then document how to install the dependencies (such that you can) using apt/yum; that will speed up source builds
• In the default case where they aren't downloading a binary, we could advertise *** For a faster installation, set the environment variable LIBARROW_BINARY=true before installing or something. I think that wouldn't be against CRAN policy
• We could also message more loudly in the default source build that not all features are enabled, set LIBARROW_MINIMAL=false and reinstall if you need them

Reporter: Nicola Crane / @thisisnic
Assignee: Nicola Crane / @thisisnic

Related issues:

• [R] Update ARROW_DEPENDENCY_SOURCE to default to AUTO (duplicates)

_{Note: This issue was originally created as ARROW-14988. Please see the migration documentation for further details.}