When looking at `TView` debug template only Element nodes were displayed
as `TNode.Element` was used for both `RElement` and `RText`.
Additionally no text was stored in `TNode.value`. The result was that
the whole template could not be reconstructed. This refactoring creates
`TNodeType.Text` and store the text value in `TNode.value`.
The refactoring also changes `TNodeType` into flag-like structure make
it more efficient to check many different types at once.
PR Close#39233
70f1e2e04a