Here's an interesting idea I picked up from Reddit: make goto-line
enable display-line-numbers-mode temporarily when prompting.  Please see
the attached patch.

Comments or thoughts welcome, as always.

Best regards,
Stefan Kangas

PS. I added a new defcustom to enable this behaviour, by default set to
    nil.  But if it seems useful, it would be nifty if we could enable
    it by default.  (I have no idea if display-line-numbers-mode is
    stable enough in all scenarios, however.)