Slashmenu improvement: Autocomplete property names in tables when autocomplete values are defined

Since we have the different property names that map to autocomplete values, we can also have the property names be shown via slash menu in the first column of a matching table.

Start by locating the slash menu implementation and the table autocomplete handling, then trace how autocomplete values are defined and how their property names are mapped. The work is done when matching tables show those property names in the first column through the slash menu.

Written by the indexing model from the issue text.