CRAS: rclient: Add cras_capture_rclient

Add new rclient type, cras_capture_rlcient, to handle message from
`.cras_capture` socket. The socket accept only capture stream
connection / disconnection.

Update cras_test_client --connection_type option usage for testing this
API.

BUG=chromium:937765
TEST=cras_test_client --connection_type 2 -C /dev/null
     cras_test_client --connection_type 2 -P /dev/urandom (This should
     fail.)

Change-Id: I46b85ff9f6e1cb2d5ab5e77971cbca07a1eece11
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/adhd/+/1836848
Reviewed-by: Dylan Reid <dgreid@chromium.org>
Tested-by: Chih-Yang Hsia <paulhsia@chromium.org>
Commit-Queue: Chih-Yang Hsia <paulhsia@chromium.org>
9 files changed