Filter controller performance improvements

[michael-j-green]

• Should resolve performance issues when loading the filter bar content (closes New Pagination Feature (whether infinite or paged or filtered) is extremely slow on Library page #224):
  • by removing unnecessary database calls;
  • adding indexes on columns used when running queries;
  • more efficient queries selecting only the data required
• Implements early fixes for Pagination runs off the page #223 - more work required to complete that issue, this is a tactical fix to make testing easier