std/math/big: add Int.Rem

Author: mertcandav

std/math/big/int.jule

@@ -259,6 +259,15 @@ impl Int {
 		self.neg = len(self.abs) > 0 && x.neg != y.neg // 0 has no sign
 	}
 
+	// Sets self to the remainder x%y for y != 0.
+	// If y == 0, a division-by-zero run-time panic occurs.
+	// Implements truncated modulus (like Jule); see [Int.QuoRem] for more details.
+	fn Rem(mut *self, &x: *Int, &y: *Int) {
+		mut q := []Word(nil)
+		divW(&q, &self.abs, x.abs, y.abs)
+		self.neg = len(self.abs) > 0 && x.neg // 0 has no sign
+	}
+
 	// Sets self to the quotient x/y for y != 0.
 	// If y == 0, a division-by-zero runtime panic occurs.
 	// Implements Euclidean division; see [Int.DivMod] for more details.