The court for the trial of impeachments is authorized to issue, and enforce obedience to, any summons, subpoena or other process necessary to the exercise of its powers and authority; to provide in what form the same shall be issued, by whom and in what manner it shall be signed and attested, by whom it shall be executed and in what form return thereof shall be made; and make such further provisions and rules as may be necessary or convenient for the discharge of its functions or duties.