cockpit-client: add flatpak support
cockpit-client: add flatpak support

Add two features designed to support running in a flatpak:

 - if FLATPAK_ID is set, allow it to override the application ID

 - try to detect if flatpak has created a new network namespace for us,
   and if so, allow running without --wildly-insecure.

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