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/api/call.wren

@@ -8,7 +8,7 @@ class Api {
   }
 
   static one(one) {
-    System.print("one " + one.toString)
+    System.print("one %(one)")
   }
 
   static two(one, two) {
@@ -17,7 +17,7 @@ class Api {
       two = two.bytes.toList
     }
 
-    System.print("two " + one.toString + " " + two.toString)
+    System.print("two %(one) %(two)")
   }
 
   static getValue(value) {