ContentPresenter does not update when DataTemplates of parent scope changes.

[pr8x]

Describe the bug

ContentPresenter does not update when DataTemplates of parent scope changes.

To Reproduce

av_datatemplates_not_updating.patch.txt

Expected behavior

Since DataTemplates is an observable collection I would expect ContentPresenter to listen to changes in the collection and update its Child once a template with higher "precedence" is inserted (i.e. a template that is higher up in the collection). Likewise removing templates from DataTemplates should proably clear the child of ContentPresenter