SPRINGFIELD — The state’s highest court will again grapple with how lengthy juvenile sentences square with the ban against “cruel and unusual” punishment.Illinois’ Supreme Court has agreed to look at whether a required 50-year sentence for a 16-year-old amounts to an unconstitutional term of life in prison.The case, People v. Dimitri Buffer, is one of seven appeals the high court agreed to look into recently. It declined to review 183 appeals, while giving orders to the lower courts in six …