_set_context_pattern(path) {
        this.#context_pattern = path;
    }
Sets context pattern for this router which will auto define the pattern of each route called on this router.
This is called by the .route() returned Router instance which allows for omission of pattern to be passed to route() method.
Example: Router.route('/something/else').get().post().delete() etc will all be bound to pattern '/something/else'
@private
@param {string} path