feat: add Sequence.list method to convert any sequence into a List

Implements a new `list` method on the Sequence class that iterates over all elements and collects them into a new List instance. Includes documentation in the core sequence docs and a test case verifying correct behavior with a custom sequence implementation.

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 {}