Implement full-text searching

Index document content as well as the document metadata, allowing for documents and files to be found by their content. Matches on content should be weighted lower than matches on metadata.

This should be accompanied by performance tests as well.
Well `getStorageBackend` already gets the info it needs off of the `uri` if `ctx` isn't passed in, but I should be able to change the backends to use `tenantAlias`