dddd[Sunstone] Improvement performance of List alpha index

:Release Notes:
Improvement performance of DataList with alpha indexer

:Detailed Notes:
Improvement performance of DataList with alpha indexer

:Testing Performed:
Open sample page and review

:QA Notes:

:Issues Addressed:
[CCWMP-7599] Performance improvement of DataList Aplhabetical index
[CCWMP-4300] Develop Listview UI - button