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/V3ActiveTop.cpp

@@ -35,14 +35,14 @@
 //######################################################################
 // Active class functions
 
-class ActiveTopVisitor final : public AstNVisitor {
+class ActiveTopVisitor final : public VNVisitor {
 private:
     // NODE STATE
     //  Entire netlist
     //   AstNode::user()                bool. True if processed
     //  Each call to V3Const::constify
     //   AstNode::user4()               Used by V3Const::constify, called below
-    const AstUser1InUse m_inuser1;
+    const VNUser1InUse m_inuser1;
 
     // STATE
     SenTreeFinder m_finder;  // Find global sentree's / add them under the AstTopScope