fix data-table-view editor

[drw]

1. DataTables views do not support previews after the migration. (The "Preview" button is there, but clicking it does nothing.)

2. The DataTables view editor does not show the control that lets the administrator select the column to sort the table by. (The column that is used for sorting is indicated in the lower right of the actual DataTables view.)

3. There's no way to change the default for whether a DataTables view shows all the columns or hides most of them and shows the blue circle with the white plus in the middle as a reveal-the-field-values-for-this-row-only button. (In the actual DataTables view, the user can click on the "Table/List toggle" button [the leftmost] in the row of icons over the table. Probably the "List view/Responsive display" checkbox in the view editor is supposed to control this, but it has no apparent effect.)