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/common_utils.robot b/lib/common_utils.robot
index 26300da..afe6f80 100755
--- a/lib/common_utils.robot
+++ b/lib/common_utils.robot
@@ -857,7 +857,7 @@
 Redfish Get BMC Version
     [Documentation]  Get BMC version via Redfish.
 
-    ${output}=  Redfish.Get Attribute  ${REDFISH_BASE_URI}Managers/bmc  FirmwareVersion
+    ${output}=  Redfish.Get Attribute  ${REDFISH_BASE_URI}Managers/${MANAGER_ID}  FirmwareVersion
     [Return]  ${output}
 
 Redfish Get Host Version