State terminology not user friendly

[FabrizioMoggio]

Problem description
The terms used into the returned states of conditional call forwarding are not standard.

Expected behavior
from conditional_unavailable to conditional_not_reachable
from conditional_no_reply to conditional_no_answer

Alternative solution

Additional context
#110

[rartych]

According to 3GPP TS 22.082 version 17.0.0 Release 17 standard names for these services are:

• Call Forwarding on No Reply
• Call Forwarding on Mobile Subscriber Not Reachable

But CAMARA should avoid telco specific terminology and should be developer friendly first.

For me conditional_not_reachable is the good choice.
I have no preference for conditional_no_reply or conditional_no_answer.

[FabrizioMoggio]

Fixed with: #117

[FabrizioMoggio]

Merged