ppc0017: Change status to Implemented

Implemented within the "builtin" namespace as below:

https://perldoc.perl.org/blead/builtin#created_as_string

https://perldoc.perl.org/blead/builtin#created_as_number

Author: rwp0

ppcs/ppc0017-original-build-type.md

@@ -5,7 +5,7 @@
     Author:  Graham Knop <haarg@haarg.org>
     Sponsor:
     ID:      0017
-    Status:  Accepted
+    Status:  Implemented
 
 ## Abstract