flatpak: improve the test script
flatpak: improve the test script

Do a reasonably realistic functional test: opening a URL requesting to
login to a particular server should actually result in ssh being run
against that server.

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