Download macOS binaries for etcd and consul.
Download macOS binaries for etcd and consul.

Instead of downloading Linux binaries when running macOS, detect platform
and download the appropriate binary.

Signed-off-by: Gerald Kaszuba <bee25f9566f14bcc1d385b4a10d34d2cb725465a@gak0.com>

vitessio/vitess,vitessio/vitess,mahak/vitess,enisoc/vitess,tinyspeck/vitess,davygeek/vitess,davygeek/vitess,tinyspeck/vitess,vitessio/vitess,mahak/vitess,enisoc/vitess,vitessio/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,tinyspeck/vitess,vitessio/vitess,vitessio/vitess,davygeek/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,mahak/vitess,davygeek/vitess,mahak/vitess,enisoc/vitess,enisoc/vitess,mahak/vitess,davygeek/vitess,enisoc/vitess,mahak/vitess,enisoc/vitess,davygeek/vitess,tinyspeck/vitess,tinyspeck/vitess,davygeek/vitess,enisoc/vitess