Use Blazor Web App

The blog currently uses **Blazor Server** - to be future proof we should switch to the **Blazor Web App** "style".
There is an open branch [feature/blazor-hybrid](https://github.com/linkdotnet/Blog/tree/feature/blazor-hybrid) that did already some ground work, but 
1. Needs a rebase/merge of the current `master` branch
2. The whole Authorization didn't quite work nicely as far as I can remember