Here I need to check that symbol of `This` is a package because it's required to remove `this` inside printed package name. For example, String in typed tree is represented with:
```scala
TypeTree().setOriginal(Select(Select(This(TypeName("scala")), scala.Predef)) 
```
If not to check this case we'll have `scala.this.Predef.String` as a printed result.
Module classes are processed in ParsedTreePrinter