search: count --all-repos in the empty-query fast-fail guard

The non-interactive "query required" guard built its own hasFilters without --all-repos, so entire search --all-repos --json (or piped/accessible) with an empty query errored instead of running a wildcard search. Mirror search.Config.HasFilters here (the guard runs before git/auth, so it can't call searchCfg.HasFilters() directly).