Title sorting enhancement - Sort by index title

Purpose/Overview:
The current implementation sorts by instance.title property but the preferred behavior is to sort by instance.indexTitle

Requirements/Scope:
The sorting by title should behave as follows:

1. if instance.indexTitle is populated, it is used for sorting
2. if instance.indexTitle is not populated, sort by instance.title field

Approach:

Acceptance criteria:

• If index title is populated, the results are sorted by it
• If the index title is not populated, sorting bases on instance.title
• The results can be sorted by desc and asc