bscnat: Refactor MSC side code to allow different actions per test

Each test can now plug in different acctions to be done by the emulated
MSC, by passing a BssmapCreateCallback RAN_Emaulation callback to
f_init(). Old hardcoded behaviour (main()) is renamed and used in
laready existing tests.

New infrastructure provides a generic BssmapCreateCallback taking care
of required boilerplate, so new tests/users only need to define a new
callback calling that generic one with a function pointer where all test
logic is implemented.

Change-Id: Ic429420d0d95b6aacb6e5c44031b49c942ed544d
3 files changed