As a user who is searching SEAD, I want to be able to search everything content-related in a single search so that I can more easily find things.

Note: currently, users can search using the search box at the top of the screen, which is a search of metadata that is not part of the fielded metadata options users can add; or they can search metadata (being changed to "Advanced Search"), which allows them to search on a particular metadata field (only 1 at a time); or they can go to 1 of 2 views of tags.

Acceptance Criteria:
1. The simple search field should search everything SEAD content related (datasets, files, folders, collections), including metadata, full-text, and metadata that's not part of the drop down fields for a space.