Moved a variable to resource file

From redfish/task_service/test_tasks.robot file moved
${TASK_JSON_FILE_PATH} to lib/resource.robot and given a default value

we can mention the relative path if we triggering the script from
different directory other than openbmc-test-automation folder.
e.g.
 robot -v TASK_JSON_FILE_PATH:openbmc-test-automation/data/task_state.json

by default variable ${TASK_JSON_FILE_PATH} will be data/task_state.json

Tested:
   Ran robot redfish/task_service/test_tasks.robot

Change-Id: I52922e315a3f042db0992d44b1f75cb93b253166
Signed-off-by: Nagarjun B  <nagarjunb@ami.com>
diff --git a/lib/resource.robot b/lib/resource.robot
index c343f86..03e2e66 100755
--- a/lib/resource.robot
+++ b/lib/resource.robot
@@ -170,6 +170,10 @@
 @{NTP_SERVER_ADDRESSES}    ${EMPTY}
 
 
+# Task Service related variables.
+${TASK_JSON_FILE_PATH}   data/task_state.json
+
+
 *** Keywords ***
 Get Inventory Schema
     [Documentation]  Get inventory schema.
diff --git a/redfish/task_service/test_tasks.robot b/redfish/task_service/test_tasks.robot
index f4559ec..d1fefc6 100644
--- a/redfish/task_service/test_tasks.robot
+++ b/redfish/task_service/test_tasks.robot
@@ -237,9 +237,9 @@
     [Documentation]  Load the task service related properties from json file.
 
     # User input -v TASK_JSON_FILE_PATH:<path> else default path.
-    ${task_json_file}=  Get Variable Value  ${TASK_JSON_FILE_PATH}  data/task_state.json
+    # ${task_json_file}=  Get Variable Value  ${TASK_JSON_FILE_PATH}  data/task_state.json
 
-    ${json}=  OperatingSystem.Get File  ${task_json_file}
+    ${json}=  OperatingSystem.Get File  ${TASK_JSON_FILE_PATH}
     ${properties}=  Evaluate  json.loads('''${json}''')  json
 
     Set Suite Variable  ${allowed_completed_task_overwrite_policy}