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/V3Case.cpp

@@ -50,7 +50,7 @@
 
 //######################################################################
 
-class CaseLintVisitor final : public AstNVisitor {
+class CaseLintVisitor final : public VNVisitor {
 private:
     const AstNodeCase* m_caseExprp
         = nullptr;  // Under a CASE value node, if so the relevant case statement
@@ -117,12 +117,12 @@ public:
 //######################################################################
 // Case state, as a visitor of each AstNode
 
-class CaseVisitor final : public AstNVisitor {
+class CaseVisitor final : public VNVisitor {
 private:
     // NODE STATE
     // Cleared each Case
     //  AstIf::user3()          -> bool.  Set true to indicate clone not needed
-    const AstUser3InUse m_inuser3;
+    const VNUser3InUse m_inuser3;
 
     // STATE
     VDouble0 m_statCaseFast;  // Statistic tracking