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/break/nested_for_loop.wren

@@ -1,9 +1,9 @@
 for (i in 0..2) {
-  IO.print("outer " + i.toString)
+  IO.print("outer ", i)
   if (i > 1) break
 
   for (j in 0..2) {
-    IO.print("inner " + j.toString)
+    IO.print("inner ", j)
     if (j > 1) break
   }
 }

test/break/nested_while_loop.wren

@@ -1,11 +1,11 @@
 var i = 0
 while (true) {
-  IO.print("outer " + i.toString)
+  IO.print("outer ", i)
   if (i > 1) break
 
   var j = 0
   while (true) {
-    IO.print("inner " + j.toString)
+    IO.print("inner ", j)
     if (j > 1) break
 
     j = j + 1