Add example configuration files for E1 BTS

This adds osmo-bsc config files for Ericsson RBS2308, Siemens BS-11 and
Nokia InSite which were working in July 2020 to get the BTS initialized,
recognized by MS and up to signalling.

Voice/TRAU support is still missing in OsmoBSC, but should be added
relatively soon.

Change-Id: I1fe15cc3654025e52fc1110ac3052fb1f7a009a0
Depends: osmo-python-tests I896b99032d94ba0cdd340a8eed7c7b625661ad69
Closes: OS4651
4 files changed