Added Vector Store File List properties that allow for pagination (#891)

vector_store.go

@@ -83,6 +83,9 @@ type VectorStoreFileRequest struct {
 
 type VectorStoreFilesList struct {
 	VectorStoreFiles []VectorStoreFile `json:"data"`
+	FirstID          *string           `json:"first_id"`
+	LastID           *string           `json:"last_id"`
+	HasMore          bool              `json:"has_more"`
 
 	httpHeader
 }