org-link-expand-abbrev: Do not evaluate arbitrary unsafe Elisp code

org-link-expand-abbrev: Do not evaluate arbitrary unsafe Elisp code

* lisp/org/ol.el (org-link-expand-abbrev): Refuse expanding %(...)
link abbrevs that specify unsafe function.  Instead, display a
warning, and do not expand the abbrev.  Clear all the text properties
from the returned link, to avoid any potential vulnerabilities caused
by properties that may contain arbitrary Elisp.

(cherry picked from commit c645e1d8205f0f0663ec4a2d27575b238c646c7c)