Migrate .NET 3.1/5 WPF guide from dotnet docs (#48)

* add toc/bread changes

* add xaml-services

* add ported wpf content

* add xaml-services info to docfx

* Fix links 1

* Fix links 2

* Fix links 3

* Fix links 4

* Fix links 5

* Fix links 6

* Fix links 7

* Fix xaml-services link

* Fix snippets 1

* Fix snippets 2

* adjust breadcrumb and toc

* remove preserve-view from breadcrumbs

* add empty view to toc item xaml

* update include

* remove contextual toc for vs article :(

dotnet-desktop-guide/xaml-services/breadcrumb/toc.yml

@@ -0,0 +1,16 @@
+items:
+- name: Docs
+  tocHref: /
+  topicHref: /
+  items:
+    - name: .NET
+      tocHref: /dotnet/
+      topicHref: /dotnet/index
+      items:
+      - name: Desktop Guide
+        tocHref: /dotnet/desktop
+        topicHref: /dotnet/desktop/index
+        items:
+        - name: XAML Language Reference
+          tocHref: /dotnet/desktop/xaml-services
+          topicHref: /dotnet/desktop/xaml-services/index