osmo-bts-trx: Big refactor and cleanup of osmo-trx related code

* This commit is a preparation for future commits to add support for
different osmo-trx devices and backends like osmo-trx-lms.

* Drop deprecated osmo-trx-* cmd line params and use VTY cfg to set them.

* As number of osmo-trx related osmo-gsm-tester attributes grow, group
them togther in an "osmo_trx" dictionary.

Change-Id: I77d29413c9e3b600b796627ba366f80c3281b7e1
diff --git a/selftest/conf/resources.conf b/selftest/conf/resources.conf
index 51f4abc..84d0ab9 100644
--- a/selftest/conf/resources.conf
+++ b/selftest/conf/resources.conf
@@ -23,7 +23,9 @@
   ipa_unit_id: 6
   addr: 10.42.42.50
   band: GSM-1800
-  launch_trx: true
+  osmo_trx:
+    launch_trx: true
+    clock_reference: external
   ciphers:
   - 'a5_0'
   - 'a5_1'
@@ -33,7 +35,10 @@
   ipa_unit_id: 7
   addr: 10.42.42.51
   band: GSM-1800
-  trx_remote_ip: 10.42.42.112
+  osmo_trx:
+    launch_trx: false
+    clock_reference: external
+    trx_ip: 10.42.42.112  
   ciphers:
   - 'a5_0'
   - 'a5_1'