Open the same data file with Tabulator table and Perspective data view simultaneously

[RandomFractals]

Currently, table views and lookups are keyed by data file Uri, and only Tabulator table or Perspective view can be open depending on the tabular.data.view preference setting added in #75

Since we might keep Tabulator table view display for now, it would be useful to view the same data file in both Tabulator table and Perspective view at the same time, especially when a d3fc chart view is used in Perspective viewer.

With this option, developers should be able to view simple data table in Tabulator and use Perspective viewer for one of the basic d3fc charts in vscode editor on the side.