Search improvements 2 (rebased onto develop)


This is the same as gh-2814 but rebased onto develop.

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Final fixes for web search. To test:

- Search results first column should be named 'Type', same as Insight
- Search results table should have separate columns for Acquired and Imported dates. Both are populated for images but not for P/D/S/P. Sorting should work for both.
- If you select search results from different groups, batch annotate panel will display but you won't be able to annotate objects, with message to explain why. Same for if you select multiple objects that you can't annotate (read-only group).
- Searching with 'Annotation' checkbox selected will include a search of file name, contents, path & format.