NEW YORK — The Knicks’ roster is not deep enough — and that’s why they need to make a trade. It’s the biggest takeaway through a four-game stretch in which New York has been mired by injury. Jalen Brunson had missed two consecutive games with calf pain, and Josh Hart missed Thursday’s 113-109 victory against the Washington Wizards, listed as day-to-day with soreness in his knee. Without Brunson, the Knicks were a shell of themselves, losing to the short-handed Orlando Magic and struggling to create separation against a Memphis Grizzlies team missing four of their top players. And on the second…