remote-run uses rsync instead of sftp server. Some of the tests were
incorrectly labelled as requiring sftp server. Fixed those and replaced
the requirement with rsync.
The current remote-run implementation only works if rsync is located at
`/usr/bin/`, which isn't always the case. FreeBSD installs rsync to
`/usr/local/bin` as it is not installed in the base system by default.
Relax the script to accept rsync on any path.
Not only does this give us a huge speed-up, it also works around a problem
where sftp doesn't always update the modification time, which causes random
test failures.
rdar://88179140
Not all the tests are possible to run on Windows since they expect a
Unix-like shell environment. However, the rest of the tests can be
accommodated. This actually found an issue in the implementation.
Since the implementation assumes the target is POSIX/Unix-y, we should
use posixpath rather than os.path which uses the host's path style.
