Make dd a little more useful for natives

If you specify dd $a, and $a is a native int or str, then you only get
to see the value *without* the name.  This is annoying while debugging.
To make this easier, you can now specify natives as a named parameter.

  my int $a = 42; dd :$a;   # Int a = 42

and by the magic of the :$var notation, we can now see the name.

src/core/Any.pm

@@ -511,18 +511,23 @@ sub DELETEKEY(Mu \d, str $key) {
     }
 } #DELETEKEY
 
-sub dd(|) {
-    my Mu $args := nqp::p6argvmarray();
-    if nqp::elems($args) {
-        while $args {
-            my $var  := nqp::shift($args);
+sub dd(*@p, *%n) {
+    if @p || %n {
+        for @p -> $var {
             my $name := $var.VAR.?name;
             my $type := $var.WHAT.^name;
             my $what := $var.?is-lazy
               ?? $var[^10].perl.chop ~ "...Inf)"
               !! $var.perl;
             note $name ?? "$type $name = $what" !! $what;
         }
+        for %n.kv -> $name, $var {
+            my $type := $var.WHAT.^name;
+            my $what := $var.?is-lazy
+              ?? $var[^10].perl.chop ~ "...Inf)"
+              !! $var.perl;
+            note $name ?? "$type $name = $what" !! $what;
+        }
     }
     else { # tell where we are
         note .name ?? "{lc .^name} {.name}" !! "({lc .^name})"