Compiler lookup some builtin elements by name doesn't play with the import system

[ogoffart]

Currently, the compiler recognize some builtin element just by their name, regardless if they are redefined or not or imported or not. It is possible to redefine builtin elements, but the compiler might still consider them as builtin and this can cause bugs.

We do that at least for ListView, ~~PopupWindow~~, TabWidget, ~~Opacity, Clip, *Layout~~, TextInput, maybe more.

So this causes the bug in this comment: https://github.com/sixtyfpsui/sixtyfps/issues/860#issuecomment-1019116038

(Another issue is that we can re-declare Builtin or already defined elements)