chore: Add global.json and Directory.Packages.props for post-processo…

…r code

Code in the generator-input directory needs to be runnable even if it's separate from the rest of the repo.

generator-input/tweaks/Directory.Packages.props

@@ -0,0 +1,34 @@
+<Project>
+  <ItemGroup>
+    <!-- Default Grpc.Core versions: these should typically be changed together -->
+    <PackageVersion Include="Grpc.Core" Version="[2.46.6, 3.0.0)" />
+    <PackageVersion Include="Grpc.Core.Testing" Version="[2.46.6, 3.0.0)" />
+
+
+    <PackageVersion Include="Google.Api.Gax.Grpc" Version="[4.9.0, 5.0.0)" />
+
+    <PackageVersion Include="Google.Api.CommonProtos" Version="2.16.0" />
+    <PackageVersion Include="Google.Api.Gax.Grpc" Version="4.9.0" />
+    <PackageVersion Include="Google.LongRunning" Version="3.3.0" />
+    <PackageVersion Include="Google.Protobuf" Version="3.28.2"/>
+    <PackageVersion Include="Google.Api.Gax.Grpc" Version="4.9.0" />
+    <PackageVersion Include="Microsoft.Build.Locator" Version="1.7.8" />
+
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp" Version="4.11.0" />
+
+    <!-- 
+      - Note: do not upgrade 4.8.0 until we're using .NET SDK v8
+      - or https://github.com/dotnet/roslyn/issues/71784 is fixed.
+      - See b/328172159 as an example of the failure.
+      -->
+    <PackageVersion Include="Microsoft.CodeAnalysis.CSharp.Workspaces" Version="4.8.0" />
+    <PackageVersion Include="Microsoft.CodeAnalysis.Workspaces.MSBuild" Version="4.8.0" />
+
+    <!--
+      - For some reason, the above packages introduce a dependency somewhere on version 3.0.3
+      - of Microsoft.Extensions.Logging.Abstractions, so MSBuild gets confused. It's simplest
+      - to just specify v6 ourselves.
+      -->
+    <PackageVersion Include="Microsoft.Extensions.Logging.Abstractions" Version="6.0.4" />
+  </ItemGroup>
+</Project>

generator-input/tweaks/global.json

@@ -0,0 +1,7 @@
+{
+  "sdk": {
+    "version": "6.0.414",
+    "allowPrerelease": false,
+    "rollForward": "latestMinor"
+  }
+}