Fix: (org-ql-view--expand-buffers-files) Remove eval support

This prevents arbitrary code execution when opening "org-ql-search:"
links.  (The links feature was just pushed to master in the last day
or so, and no stable release with the feature has been tagged.)  This
fix also means that arbitrary expressions are no longer accepted when
interactively completing the buffers-files argument to
org-ql-search (a worthy trade, I think; users who need to do that can
call the function from Lisp).

org-ql-view.el

@@ -1063,7 +1063,6 @@ The counterpart to `org-ql-view--contract-buffers-files'."
     ("all" (--select (equal (buffer-local-value 'major-mode it) 'org-mode)
                      (buffer-list)))
     ("org-directory" (org-ql-search-directories-files))
-    ((and form (guard (rx bos "("))) (-flatten (eval (read form))))
     (else (s-split (rx (1+ space)) else))))
 
 (defun org-ql-view--complete-super-groups ()