Handle non-front-panel ports in is_rj45_port (sonic-net#2327)

* Handle non-front-panel ports in is_rj45_port

Handle the cases that a port is not a front-panel port in is_rj45_port
Add mock test to cover the logic

Signed-off-by: Stephen Sun <stephens@nvidia.com>

* Use APIs in sonic_platform_base

Signed-off-by: Stephen Sun <stephens@nvidia.com>

Signed-off-by: Stephen Sun <stephens@nvidia.com>

utilities_common/platform_sfputil_helper.py

@@ -133,7 +133,7 @@ def is_rj45_port(port_name):
 
         port_type = None
         try:
-            physical_port = logical_port_name_to_physical_port_list(port_name)
+            physical_port = platform_sfputil.logical_port_name_to_physical_port_list(port_name)
             if physical_port:
                 port_type = platform_chassis.get_port_or_cage_type(physical_port[0])
         except Exception as e: