Support Isearch filter predicates with empty search hits (bug#49534)

Support Isearch filter predicates with empty search hits (bug#49534)

* lisp/isearch.el (isearch-search): Move (= (match-beginning 0) (match-end 0))
and (bobp)/(eobp) outside the call to isearch-filter-predicate.
Use forward-char 1/-1 on empty matches only when going to retry search.
(isearch-lazy-highlight-search):  Remove (= (point) bound),
but leave (= (match-beginning 0) (match-end 0)) since empty matches
make no sense in lazy-highlighting.