feat: add overloaded IO.print methods accepting 2-16 arguments and printList_ helper

Add 15 static overloads of IO.print in builtin/io.wren and src/wren_io.c, each delegating to a new private printList_ method that iterates over a list of objects. Update all benchmark and test files to use the new multi-argument syntax, removing explicit .toString calls and string concatenation. Add a comprehensive test/io/print.wren verifying single-argument return value, multi-argument null return, and concatenation of up to 16 arguments.

test/io/print.wren

@@ -0,0 +1,25 @@
+// With one argument, returns the argument.
+IO.print(IO.print(1) == 1) // expect: 1
+                           // expect: true
+
+// With more than one argument, returns null.
+IO.print(IO.print(1, 2) == null) // expect: 12
+                                 // expect: true
+
+// Allows multiple arguments and concatenates them.
+IO.print(1) // expect: 1
+IO.print(1, 2) // expect: 12
+IO.print(1, 2, 3) // expect: 123
+IO.print(1, 2, 3, 4) // expect: 1234
+IO.print(1, 2, 3, 4, 5) // expect: 12345
+IO.print(1, 2, 3, 4, 5, 6) // expect: 123456
+IO.print(1, 2, 3, 4, 5, 6, 7) // expect: 1234567
+IO.print(1, 2, 3, 4, 5, 6, 7, 8) // expect: 12345678
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9) // expect: 123456789
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) // expect: 12345678910
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11) // expect: 1234567891011
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12) // expect: 123456789101112
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13) // expect: 12345678910111213
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14) // expect: 1234567891011121314
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15) // expect: 123456789101112131415
+IO.print(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16) // expect: 12345678910111213141516