Move SeenMap to the utils dir

api/internal/crawl/utils/utils.go

@@ -0,0 +1,16 @@
+package utils
+
+type SeenMap map[string]struct{}
+
+func (seen SeenMap) Seen(item string) bool {
+	_, ok := seen[item]
+	return ok
+}
+
+func (seen SeenMap) Add(item string) {
+	seen[item] = struct{}{}
+}
+
+func NewSeenMap() SeenMap {
+	return make(map[string]struct{})
+}