V3 - Use new .NET CDN URLs and update to latest install scripts (#567)

* Update new cdn

* new cdn changes

* update latest install scripts

* Format install scripts

* Fix Ubuntu-latest issues

* Fallback logic

* Format check

* Update signed version

.github/workflows/test-dotnet.yml

@@ -17,7 +17,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        operating-system: [ubuntu-latest, windows-latest, macOS-latest]
+        operating-system: [ubuntu-22.04, windows-latest, macOS-latest]
         dotnet-version: ['2.1', '2.2', '3.0', '3.1', '5.0', '6.0', '7.0', '8.0']
     steps:
       - name: Checkout