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/redfish/managers/test_bmc_ipv6.robot b/redfish/managers/test_bmc_ipv6.robot
index edabf98..8ab1f92 100644
--- a/redfish/managers/test_bmc_ipv6.robot
+++ b/redfish/managers/test_bmc_ipv6.robot
@@ -105,7 +105,7 @@
     [Documentation]  Get Ipv6 network configuration.
     # Sample output:
     # {
-    #  "@odata.id": "/redfish/v1/Managers/bmc/EthernetInterfaces/eth0",
+    #  "@odata.id": "/redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces/eth0",
     #  "@odata.type": "#EthernetInterface.v1_4_1.EthernetInterface",
     #   "DHCPv4": {
     #    "DHCPEnabled": false,
@@ -176,7 +176,7 @@
     #    "State": "Enabled"
     #  },
     #  "VLANs": {
-    #    "@odata.id": "/redfish/v1/Managers/bmc/EthernetInterfaces/eth0/VLANs"
+    #    "@odata.id": "/redfish/v1/Managers/${MANAGER_ID}/EthernetInterfaces/eth0/VLANs"
 
 
     ${active_channel_config}=  Get Active Channel Config