ms_driver: Add a virtual bts and make use of it

It's very close to the osmo-bts-trx but without osmo-trx. Modify
the suite to make use of this BTS.

Change-Id: I9f5a2501eb4473ccf2287c902ee207c6a45a1bc5
diff --git a/src/osmo_gsm_tester/resource.py b/src/osmo_gsm_tester/resource.py
index e71f4cd..4f48dc4 100644
--- a/src/osmo_gsm_tester/resource.py
+++ b/src/osmo_gsm_tester/resource.py
@@ -29,7 +29,7 @@
 from . import schema
 from . import modem
 from . import osmo_nitb
-from . import bts_sysmo, bts_osmotrx, bts_octphy, bts_nanobts
+from . import bts_sysmo, bts_osmotrx, bts_osmovirtual, bts_octphy, bts_nanobts
 
 from .util import is_dict, is_list
 
@@ -102,6 +102,7 @@
         'osmo-bts-sysmo': bts_sysmo.SysmoBts,
         'osmo-bts-trx': bts_osmotrx.OsmoBtsTrx,
         'osmo-bts-octphy': bts_octphy.OsmoBtsOctphy,
+        'osmo-bts-virtual': bts_osmovirtual.OsmoBtsVirtual,
         'nanobts': bts_nanobts.NanoBts,
     }