Report the errors raised by _ProcessRemoteHostArtifacts

Test: acloud-dev create -vv --local-image ~/target_files.zip \
      --cvd-host-package ~/cvd-host_package.tar.gz \
      --local-system-image ~/system.img \
      --host 192.168.9.2 --host-user vsoc-01 \
      --host-ssh-private-key-path ~/id_rsa \
      --remote-image-dir img
Bug: 293966645
Change-Id: I722ed5c05b250e645eb99512e64d5e1a8f7a17f4