RakuAST: Implement deparse of Regex::SequentialConjunction

Includes a fix for deparse of Regex::Conjuction - that one should
generate &, not &&

src/core.c/RakuAST/Deparse.pm6

@@ -36,7 +36,8 @@ class RakuAST::Deparse {
     has str $.regex-close = ' /';
     has str $.regex-alternation = ' | ';
     has str $.regex-sequential-alternation = ' || ';
-    has str $.regex-conjunction = ' && ';
+    has str $.regex-conjunction = ' & ';
+    has str $.regex-sequential-conjunction = ' && ';
 
     has str $.before-infix = ' ';
     has str $.after-infix  = ' ';
@@ -992,6 +993,10 @@ class RakuAST::Deparse {
         self!branches($ast, $.regex-sequential-alternation)
     }
 
+    multi method deparse(RakuAST::Regex::SequentialConjunction:D $ast --> str) {
+        self!branches($ast, $.regex-sequential-conjunction)
+    }
+
     multi method deparse(RakuAST::Signature:D $ast --> str) {
         if $ast.parameters -> @parameters {
             my $parts := nqp::list_s;