test: fixes to call-forwarding scripts

[tonyespy]

Added multi-modem support to set-call-forwarding, changed test-call-forwarding to verify the expected CF properties and implement a KeyboardInterrupt handler so a backtrace isn't output when Ctrl-C is used to terminate the main loop.

Also added cf.SetProperty calls for "VoiceBusy" and "VoiceNotReachable" to fully cover all of the properties.

[alfonsosanchezbeato]

Why did you do this change? The set you use between the brackets is exactly the same contained in "properties".

[tonyespy]

I did this so that I could get rid of the first test case in:

https://wiki.ubuntu.com/Process/Merges/TestPlans/ofono/CallForwarding

This change now causes the script to verify that the interface and all the properties are properly exported.

[alfonsosanchezbeato]

Got it, but taking into account that that is Ubuntu Touch's test plan, I am not sure if upstream would accept this change if that is the only reason. If we want to fully automatize CallForwarding testing I think we should create a different script similar to the ones you created for testing the SIM interface, because I do not think that test-call-forwarding fully fits our testing needs.

[alfonsosanchezbeato]

Looks good, although I have a couple of comments.

Also, it would be good to handle Ctrl+C in set-call-forwarding in the same way you do for test-call-forwarding, and add a time out to exit for both scripts.

Finally, I think it's worth upstreaming this.