Navigation of references via previous-error and next-error

[nordlow]

elisp-refs-symbol and similar should support navigation of references via Emacs standard functions previous-error and next-error similar to what Emacs standard packages xref (providing xref-find-references), grep, locate etc support.

The whole idea is to visit match automatically in a "preview" window when navigating the hits via next-match and previous-match without hiding the *xref* buffer window.

This style of navigation is becoming standard behaviour in large extra packages. For instance, ivy binds such navigation (with preview in other window) to C-M-n for next match and C-M-p for previous match.