Managers ID : Introduced variable to declare Managers ID in resource.robot and updated all the scripts in openbmc-test-automation

Changes:
    - Introduced ${MANAGER_ID} variable in resource.robot
    - Replaced all the Managers/bmc to Managers/${MANAGER_ID} across all the scripts
    - Also in data/variables.py updated chassis id for the few redfish uri.

Tested:
     - Ran All The Scripts Successfully

Change-Id: Iff3673aae27657e0799dec5cb94c1651a0cd5d18
Signed-off-by: ganesanb <ganesanb@ami.com>
Signed-off-by: George Keishing <gkeishin@in.ibm.com>
diff --git a/lib/redfish_plus.py b/lib/redfish_plus.py
index 2cc7531..c33895a 100755
--- a/lib/redfish_plus.py
+++ b/lib/redfish_plus.py
@@ -95,7 +95,7 @@
 
         From a python program:
 
-        response = bmc_redfish.get("/redfish/v1/Managers/bmc/EthernetInterfaces", [200, 201])
+        response = bmc_redfish.get("/redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces", [200, 201])
 
         If this call to the get method generates a response.status equal to anything other than 200 or 201,
         an exception will be raised.
@@ -103,7 +103,7 @@
         From a robot program:
 
         BMC_Redfish.logout
-        ${response}=  BMC_Redfish.Get  /redfish/v1/Managers/bmc/EthernetInterfaces  valid_status_codes=[401]
+        ${response}=  BMC_Redfish.Get  /redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces  valid_status_codes=[401]
 
         As part of a robot test, the programmer has logged out to verify that the get request will generate a
         status code of 401 (i.e. "Unauthorized").