Pass GitHubVS_Client* to MSBuild as property

Author: jcansdale

azure-pipelines.yml

@@ -48,7 +48,7 @@ steps:
     platform: '$(buildPlatform)'
     configuration: '$(buildConfiguration)'
     msbuildVersion: '16.0'
-    msbuildArguments: '/property:DeployExtension=False'
+    msbuildArguments: '/property:DeployExtension=False;GitHubVS_ClientId=$(GitHubVS_ClientId);GitHubVS_ClientSecret=$(GitHubVS_ClientSecret)'
 
 - task: MSBuild@1
   displayName: GitHub Essentials