Feature-9904: Enhancing NG-UI to enable Juju operational view dashboard

Added methods in n2vc_juju_conn and libjuju to suppot configs list
and executed actions/history of actions. Added method in n2vc juju conn
to call libjuju methods to get actions, configs and history of actions.

Change-Id: I845789080d148fa42e859dcda185da1e62b4c489
Signed-off-by: ksaikiranr <saikiran.k@tataelxsi.co.in>
diff --git a/n2vc/exceptions.py b/n2vc/exceptions.py
index 721b1f4..1f48661 100644
--- a/n2vc/exceptions.py
+++ b/n2vc/exceptions.py
@@ -111,6 +111,18 @@
         return "<{}> Not found: {}".format(type(self), super().__str__())
 
 
+class JujuError(N2VCException):
+    """
+    Juju Error
+    """
+
+    def __init__(self, message: str = ""):
+        N2VCException.__init__(self, message=message)
+
+    def __str__(self):
+        return "<{}> Juju Error: {}".format(type(self), super().__str__())
+
+
 class K8sException(Exception):
     """
     K8s exception