Enhance F# formatting targets to ensure single execution per project and improve build process

Author: TheAngryByrd

Directory.Build.targets

@@ -23,9 +23,24 @@ See https://learn.microsoft.com/en-us/visualstudio/msbuild/customize-by-director
   </Target>
 
   <!-- Make sure that files are formatted before building -->
-  <Target Name="Format" Condition=" '$(MSBuildProjectExtension)' == '.fsproj' AND '$(DesignTimeBuild)' != 'true' " BeforeTargets="BeforeBuild" Inputs="@(Compile)" Outputs="$(_DotnetFantomasOutputFile)" >
+  <Target Name="FormatFSharp" Condition=" '$(MSBuildProjectExtension)' == '.fsproj' AND '$(DesignTimeBuild)' != 'true' " BeforeTargets="BeforeBuild" Inputs="@(Compile)" Outputs="$(_DotnetFantomasOutputFile)" >
     <Exec Command="dotnet fantomas $(MSBuildProjectDirectory)" StandardOutputImportance="High" StandardErrorImportance="High" WorkingDirectory="$(MSBuildThisFileDirectory)" ContinueOnError="WarnAndContinue" />
     <Touch Files="$(_DotnetFantomasOutputFile)" AlwaysCreate="True" ForceTouch="True" />
   </Target>
 
+  <!-- Only format once per project -->
+  <!-- https://learn.microsoft.com/en-us/visualstudio/msbuild/run-target-exactly-once?view=vs-2022 -->
+  <Target Name="FormatFSharpBeforeOuterBuild"
+    DependsOnTargets="FormatFSharp"
+    BeforeTargets="DispatchToInnerBuilds"
+  />
+
+  <Target Name="FormatFSharpBeforeInnerBuild"
+    BeforeTargets="BeforeBuild">
+    <MSBuild Projects="$(MSBuildProjectFullPath)"
+      Targets="FormatFSharp"
+      RemoveProperties="TargetFramework" />
+  </Target>
+
+
 </Project>