feat: add Sequence.list method to collect elements into a new List

Implements a new `list` method on the Sequence class that iterates over all elements and returns them as a freshly created List object. Includes documentation with usage example and a test case using a custom TestSequence class to verify correct behavior.

builtin/core.wren

@@ -90,6 +90,14 @@ class Sequence {
 
     return result
   }
+
+  list {
+    var result = new List
+    for (element in this) {
+      result.add(element)
+    }
+    return result
+  }
 }
 
 class String is Sequence {