Copy files

Verifies that a Fuchsia device can copy files to/from a host device.

On the Fuchsia device, this test exercises openssh including scp. On the host device, this tests the fx scp scripts. The test may also be inadvertently affected by any networking or storage issues on either device.

This test is important for the Workstation product, since copying files to and from Fuchsia and host devices is something that we expect users to do. The unique coverage this test offers is that it closely mimics the actual user experience, including running scp on a host, so we ensure that we don't break that flow.