feat: implement string interpolation with %(expr) syntax in compiler and core library

Add lexer support for `TOKEN_INTERPOLATION` to split string literals at interpolation points, introduce `MAX_INTERPOLATION_NESTING` limit of 8, and compile interpolated strings by emitting calls to `String.interpolate_()`. Optimize list and map literal construction with new `addCore_` primitives to reduce stack churn. Update `String`, `List`, and `Map` `toString` methods in core library to use interpolation syntax, and migrate all benchmark and test files from explicit concatenation to interpolated strings.

test/language/constructor/superclass.wren

@@ -1,6 +1,6 @@
 class A {
   construct new(arg) {
-    System.print("new A " + arg)
+    System.print("new A %(arg)")
     _field = arg
   }
 
@@ -10,7 +10,7 @@ class A {
 class B is A {
   construct new(arg1, arg2) {
     super(arg2)
-    System.print("new B " + arg1)
+    System.print("new B %(arg1)")
     _field = arg1
   }