Map indicator mappings using index in Run Report view

Currently, indicator mappings in the Run Report view are mapped with the created timestamp. Since the timestamp can be duplicated, it isn't suitable to use as a unique identifier. Moreover, the run report view iterates through the fetched array which contains indicator mappings in each function to get the selected mapping using the js filter function which is not optimized for the use case.   

 A possible solution would be using the indexes of the mappings to identify the selected one. Furthermore, we can keep the selected mapping in a global variable so that it can be accessed within other functions without going through the UI.