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/example/resources.conf.prod b/example/resources.conf.prod
index 31a737c..41ab009 100644
--- a/example/resources.conf.prod
+++ b/example/resources.conf.prod
@@ -24,16 +24,21 @@
   ipa_unit_id: 6
   addr: 10.42.42.50
   band: GSM-1800
-  launch_trx: true
   ciphers: [a5_0, a5_1]
+  osmo_trx:
+    launch_trx: true
+    clock_reference: external
 
 - label: sysmoCell 5000
   type: osmo-bts-trx
   ipa_unit_id: 7
   addr: 10.42.42.51
   band: GSM-1800
-  trx_remote_ip: 10.42.42.112
   ciphers: [a5_0, a5_1]
+  osmo_trx:
+        launch_trx: false
+        clock_reference: external
+        trx_ip: 10.42.42.112
 
 - label: OCTBTS 3500
   type: osmo-bts-octphy