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/bmc_network_utils.robot b/lib/bmc_network_utils.robot
index d2c3543..7c9ce49 100644
--- a/lib/bmc_network_utils.robot
+++ b/lib/bmc_network_utils.robot
@@ -424,7 +424,7 @@
     # Sample output:
     #{
     #  "@odata.context": "/redfish/v1/$metadata#EthernetInterface.EthernetInterface",
-    #  "@odata.id": "/redfish/v1/Managers/bmc/EthernetInterfaces/eth0",
+    #  "@odata.id": "/redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces/eth0",
     #  "@odata.type": "#EthernetInterface.v1_2_0.EthernetInterface",
     #  "Description": "Management Network Interface",
     #  "IPv4Addresses": [