RakuAST: introduce RakuAST::Doc::Row class

This object represents a row in a =table rakudoc.  For now just the
bare necessities to make it known and allow it to deparse and rakufy

src/core.c/RakuAST/Deparse.pm6

@@ -646,6 +646,10 @@ class RakuAST::Deparse {
         $ast.atoms.map({ self!deparse-unquoted($_) }).join
     }
 
+    multi method deparse(RakuAST::Doc::Row:D $ast --> Str:D) {
+        $ast.Str
+    }
+
 #- Dot -------------------------------------------------------------------------
 
     multi method deparse(RakuAST::DottyInfix::Call:D $ --> Str:D) {

src/core.c/RakuAST/Fixups.pm6

@@ -5,6 +5,13 @@ my class RakuAST::LegacyPodify { ... }
 # needed to compile the Raku setting) to be written in Raku rather
 # than in NQP.
 
+my class RakuAST::Doc::Row {
+    has str  $.column-dividers;
+    has      $.column-offsets is built(:bind);  # native int array
+    has      $.cells          is built(:bind);  # native str array
+    has Bool $.multi-line     is built(False);  # columns are multi-line
+}
+
 augment class RakuAST::Doc {
 
     # just pass it on for now, make using another class possible

src/core.c/RakuAST/Raku.pm6

@@ -364,6 +364,10 @@ augment class RakuAST::Node {
         self!positionals(self.atoms)
     }
 
+    multi method raku(RakuAST::Doc::Row:D: --> Str:D) {
+        self!nameds: <column-dividers column-offsets cells>
+    }
+
 #- Dot -------------------------------------------------------------------------
 
     # Handles all of the RakuAST::DottyInfix::xxx classes