[R] [Packaging] Developing + {LIBARROW_BINARY=true}

[asfimport]

As far as I can tell from reading configure + nixlibs.sh, if one tries to use {LIBARROW_BINARY=true}} on a source checkout there really isn't a binary to be found to install. The installation process does mention that a binary isn't found + it will build from source.

I don't know that we need to support installing a binary from a development branch (afterall, it's entirely possible libarrow would no longer be compatible with the r package) but I think we should fail a little bit more loudly (or express that the binary install will not be attempted because it looks like one is building from a source checkout (possibly detected by seeing if the version is ~x.x.x.9000)).

Alternatively, we could add date-guessing and attempt to download the nightly libarrow corresponding to that.

Reporter: Jonathan Keane / @jonkeane

_{Note: This issue was originally created as ARROW-12008. Please see the migration documentation for further details.}