test(deployments): port artifact tests to integration:ng

Artifact size, v2 listing, release deletion, depends and provides
semantics and generated artifacts, ported from test_deployments.py,
test_artifact.py and test_create_artifact.py, which keep running in
parallel.

Signed-off-by: Patryk Targowicz <patryk.targowicz@northern.tech>

Author: p-targowicz