Specify sdk version in global.json (#3156)

* create global.json

* pr feedback

Author: westin-m

build/template-install-dependencies.yaml

@@ -26,7 +26,7 @@ steps:
 - task: UseDotNet@2
   displayName: 'Use .NET SDK 9.0.x'
   inputs:
-    version: 9.0.x
+    useGlobalJson: true
 
 # Run Nuget Tool Installer
 

global.json

@@ -0,0 +1,9 @@
+{
+    "msbuild-sdks": {
+        "Microsoft.Build.NoTargets": "3.7.56"
+    },
+    "sdk": {
+        "version": "9.0.0",
+        "rollForward": "latestFeature"
+    }
+}