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/V3LifePost.cpp

@@ -40,7 +40,7 @@
 //######################################################################
 // LifePost class functions
 
-class LifePostElimVisitor final : public AstNVisitor {
+class LifePostElimVisitor final : public VNVisitor {
 private:
     bool m_tracingCall = false;  // Iterating into a CCall to a CFunc
 
@@ -128,12 +128,12 @@ struct LifePostLocation {
 //######################################################################
 // LifePost delay elimination
 
-class LifePostDlyVisitor final : public AstNVisitor {
+class LifePostDlyVisitor final : public VNVisitor {
 private:
     // NODE STATE
     // Cleared on entire tree
     //  AstVarScope::user4()    -> AstVarScope*: Passed to LifePostElim to substitute this var
-    const AstUser4InUse m_inuser4;
+    const VNUser4InUse m_inuser4;
 
     // STATE
     uint32_t m_sequence = 0;  // Sequence number of assigns/varrefs,