Add :$all to methods() for Perl 6 compatability

For some types, calling .^methods(:all) in Rakudo would end up in NQP.
None of the NQP methods() had a :$all parameter, so they would die with
`Unexpected named argument 'all' passed`. Per
https://irclog.perlgeek.de/perl6-dev/2017-06-03#i_14681666 :$all doesn't
have any effect, so this commit adds them only for compatability.

BenGoldberg++ for the find, timotimo++ and jnthn++ for the debugging
help.

src/how/NQPClassHOW.nqp

@@ -557,7 +557,7 @@ knowhow NQPClassHOW {
         @!done;
     }
 
-    method methods($obj, :$local = 0) {
+    method methods($obj, :$local = 0, :$all) {
         if $local {
             @!method_order
         }

src/how/NQPConcreteRoleHOW.nqp

@@ -123,7 +123,7 @@ knowhow NQPConcreteRoleHOW {
     ## Introspecty
     ##
 
-    method methods($obj, :$local) {
+    method methods($obj, :$local, :$all) {
         my @meths;
         for %!methods {
             nqp::push(@meths, nqp::iterval($_));

src/how/NQPParametricRoleHOW.nqp

@@ -168,7 +168,7 @@ knowhow NQPParametricRoleHOW {
     ## Introspecty
     ##
 
-    method methods($obj, :$local) {
+    method methods($obj, :$local, :$all) {
         my @meths;
         for %!methods {
             nqp::push(@meths, nqp::iterval($_));