Enable configuration of NR UE through a YAML file

This commit adds yaml-cpp library to required docker images and build commands. There is one workaround
in cross-compilation for apt behavior for installing libyaml-cpp-dev. Apt will uninistall previous
versions of the package whenever another one is installed. This means that installing the arm version
breaks amd version and vice versa. This makes it impossible to have both libs installed at the same
time which is required by the cross-compilation build command (it calls cmake twice, once with native
and once with target architecture)

docker/scripts/nr_ue_entrypoint.sh

@@ -9,8 +9,13 @@ echo "=================================="
 echo "/proc/sys/kernel/core_pattern=$(cat /proc/sys/kernel/core_pattern)"
 
 if [ ! -f $CONFIGFILE ]; then
-  echo "No configuration file found: please mount at $CONFIGFILE"
-  exit 255
+  echo "No configuration file $CONFIGFILE found: attempting to find YAML config"
+  YAML_CONFIGFILE=$PREFIX/etc/nr-ue.yaml
+  if [ ! -f $YAML_CONFIGFILE ]; then
+    echo "No configuration file $YAML_CONFIGFILE found. Please mount either at $CONFIGFILE or $YAML_CONFIGFILE"
+    exit 255
+  fi
+  CONFIGFILE=$YAML_CONFIGFILE
 fi
 
 echo "=================================="
@@ -35,6 +40,9 @@ while [[ $# -gt 0 ]]; do
   shift
 done
 
+new_args+=("-O")
+new_args+=("$CONFIGFILE")
+
 # enable printing of stack traces on assert
 export OAI_GDBSTACKS=1