UnitOfWork: Add hasPendingChanges() method

[roxblnfk]

🔍 What was changed

Added \Cycle\ORM\Transaction\UnitOfWork::hasPendingChanges()

    /**
     * Check if there are pending changes in the unit of work.
     *
     * @return bool True if there are pending changes, false otherwise.
     *         In case the transaction is finished, it will always return false.
     *         In case the transaction is in process, it will always return true.
     *         In case of failure, it will return true and pending changes can be retried.
     */
    public function hasPendingChanges(): bool