Define default fields for nanopub views

[ashleycaselli]

We cannot use a query in a View that has more than 1 target field since we don't allow for more yet. For instance, https://nanodash.knowledgepixels.com/query?354&id=RAhbj9bJBxRYbGPbluKkf4yDMKM5nZ29w0dMjaGq7XfNU/get-filtered-nanopub-list cannot be used.

To solve this, we can define something like np_starttime, np_pubkeys, etc., to reduce the risk of them being used accidentally otherwise. We can fill them only if the view is a nanopub view AND the query provides these fields AND the UI component has user input fields and values for them.