Internals: Rename Ast on non-node classes (#3262). No functional change.

This commit has the following replacements applied:

	s/\bAstUserInUseBase\b/VNUserInUseBase/g;
        s/\bAstAttrType\b/VAttrType/g;
        s/\bAstBasicDTypeKwd\b/VBasicDTypeKwd/g;
        s/\bAstDisplayType\b/VDisplayType/g;
        s/\bAstNDeleter\b/VNDeleter/g;
        s/\bAstNRelinker\b/VNRelinker/g;
        s/\bAstNVisitor\b/VNVisitor/g;
        s/\bAstPragmaType\b/VPragmaType/g;
        s/\bAstType\b/VNType/g;
        s/\bAstUser1InUse\b/VNUser1InUse/g;
        s/\bAstUser2InUse\b/VNUser2InUse/g;
        s/\bAstUser3InUse\b/VNUser3InUse/g;
        s/\bAstUser4InUse\b/VNUser4InUse/g;
        s/\bAstUser5InUse\b/VNUser5InUse/g;
        s/\bAstVarType\b/VVarType/g;

src/V3Class.cpp

@@ -29,12 +29,12 @@
 
 //######################################################################
 
-class ClassVisitor final : public AstNVisitor {
+class ClassVisitor final : public VNVisitor {
 private:
     // NODE STATE
     //  AstClass::user1()       -> bool.  True if iterated already
     //  AstVar::user1p()        -> AstVarScope*  Scope used with this var
-    const AstUser1InUse m_inuser1;
+    const VNUser1InUse m_inuser1;
 
     // MEMBERS
     string m_prefix;  // String prefix to add to name based on hier