Fix build on non-Windows

.gitignore

@@ -15,9 +15,6 @@ Library/
 # local nuget cache
 .nuget/
 
-# NuGet.Config at the root
-/NuGet.Config
-
 # NuGet v3 restore drops these even though we don't use MSBuild :(
 *.nuget.targets
 *.nuget.props

NuGet.config

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <solution>
+    <add key="disableSourceControlIntegration" value="true" />
+  </solution>
+  <!-- Only specify feed for Arcade SDK (see https://github.com/Microsoft/msbuild/issues/2982) -->
+  <packageSources>
+    <clear />
+    <add key="dotnet-core" value="https://dotnetfeed.blob.core.windows.net/dotnet-core/index.json" />
+    <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
+  </packageSources>
+  <disabledPackageSources>
+    <clear />
+  </disabledPackageSources>
+</configuration>