feat: add database non full text index (close #2916)

internal/search/db_non_full_text/init.go

@@ -0,0 +1,16 @@
+package db
+
+import (
+	"github.com/alist-org/alist/v3/internal/search/searcher"
+)
+
+var config = searcher.Config{
+	Name:       "database_non_full_text",
+	AutoUpdate: true,
+}
+
+func init() {
+	searcher.RegisterSearcher(config, func() (searcher.Searcher, error) {
+		return &DB{}, nil
+	})
+}