bridge: Robust JSON object comparison in test-httpstream.c
bridge: Robust JSON object comparison in test-httpstream.c

Comparing the received control message JSON against the expected value
in string form has always been brittle: It assumes a
predictable/reproducible GLib dictionary serialization. This will break
across different GLib versions once we add a new static header.

So change the tests to compare the control message with
`cockpit_assert_json_eq()` (which will do parsing and deep object
comparison) instead of plain string comparison. Introduce a new
assert_channel_response() helper for this.

mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,martinpitt/cockpit,mvollmer/cockpit,mvollmer/cockpit,martinpitt/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpit-project/cockpit,martinpitt/cockpit,martinpitt/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit