Feature #2267: add testing of the new OsmoMSC with AoIP
add test API to allow launching OsmoBSC and OsmoMSC
We want to be able to run OsmoBSC and OsmoMSC instead of OsmoNITB.
Add explicit test API, so that instead of 'suite.nitb()', a test can call 'suite.bsc()' and 'suite.msc()' and launch those.
In this issue, we first want to be able to write a separate test for the BSC+MSC way, and accept that each test would have to be written a second time.
To have an abstraction of NITB vs BSC+MSC, see #2270.