BREAKING CHANGE:
The public API for `DebugNode` was accidentally too broad. This change removes
1. Public constructor. Since `DebugNode` is a way for Angular to communicate information
on to the developer there is no reason why the developer should ever need to
Instantiate the `DebugNode`
2. We are also removing `removeChild`, `addChild`, `insertBefore`, and `insertChildAfter`.
All of these methods are used by Angular to constructor the correct `DebugNode` tree.
There is no reason why the developer should ever be constructing a `DebugNode` tree
And these methods should have never been made public.
3. All properties have been change to `readonly` since `DebugNode` is used by Angular
to communicate to developer and there is no reason why these APIs should be writable.
While technically breaking change we don’t expect anyone to be effected by this change.
PR Close#27223
