[build][project-system] Remove YetiVSI.ProjectSystem hack

YetiVSI.ProjectSystem.v15/16/17 exist to workaround the problem of backwards incompatibility in Visual Studio APIs. In order to build a single VSIX that is compatible with both VS2017 and VS2019 (that's where the compatibility is broken), we build two versions of `YetiVSI.ProjectSystem` and then resolve the correct one in runtime. This has a benefit of resolving everything statically in the code and having tests for each version of the API, but it complicates and slows down the build.

Since the incompatibility surface is really small (a single member changed its type), we can just workaround that difference via reflection and remove the whole `YetiVSI.ProjectSystem` machinery.

GitOrigin-RevId: e145900cd7f99c59eaf75ab68ac253fb04620007

YetiVSI.2019/YetiVSI.2019.csproj

@@ -433,19 +433,5 @@
     </Content>
   </ItemGroup>
   <Import Project="..\YetiVSI.Shared\YetiVSI.Shared.projitems" Label="Shared" />
-  <Target Name="BuildProjectSystemAdapterAssemblies" AfterTargets="MainResourcesGeneration">
-    <ItemGroup>
-      <ProjectToBuild Include="..\YetiVSI.ProjectSystem.v15\YetiVSI.ProjectSystem.v15.csproj" />
-      <ProjectToBuild Include="..\YetiVSI.ProjectSystem.v16\YetiVSI.ProjectSystem.v16.csproj" />
-    </ItemGroup>
-    <MSBuild Projects="@(ProjectToBuild)" Properties="Configuration=$(SharedConfiguration)">
-      <Output TaskParameter="TargetOutputs" ItemName="ProjectSystemAdapterAssemblies" />
-    </MSBuild>
-    <ItemGroup>
-      <EmbeddedResource Include="@(ProjectSystemAdapterAssemblies)">
-        <LogicalName>Embedded/%(Filename)%(Extension)</LogicalName>
-      </EmbeddedResource>
-    </ItemGroup>
-  </Target>
   <Import Project="..\YetiVSI.Shared\AdditionalLibSuppression.targets" />
-</Project>
+</Project>

YetiVSI.2022/YetiVSI.2022.csproj

@@ -285,10 +285,6 @@
       <Project>{1731F5D3-FDF7-4D5B-99FE-910E0924173A}</Project>
       <Name>YetiVSI.ProjectSystem.Abstractions</Name>
     </ProjectReference>
-    <ProjectReference Include="..\YetiVSI.ProjectSystem.v17\YetiVSI.ProjectSystem.v17.csproj">
-      <Project>{590E755F-957E-4D6B-B427-9E37E8A65F01}</Project>
-      <Name>YetiVSI.ProjectSystem.v17</Name>
-    </ProjectReference>
   </ItemGroup>
   <!-- Shared references -->
   <ItemGroup>

YetiVSI.ProjectSystem.Shared/ConfiguredProjectAdapter.cs → YetiVSI.Shared/ConfiguredProjectAdapter.cs

@@ -19,7 +19,7 @@
 using Microsoft.VisualStudio.ProjectSystem.Properties;
 using YetiVSI.ProjectSystem.Abstractions;
 
-namespace YetiVSI.ProjectSystem
+namespace YetiVSI
 {
     public class ConfiguredProjectAdapter : IAsyncProject
     {
@@ -29,11 +29,34 @@ public class ConfiguredProjectAdapter : IAsyncProject
 
         public ConfiguredProjectAdapter(ConfiguredProject configuredProject)
         {
+            // UnconfiguredProject is the same in VS2017 and VS2019.
             unconfiguredProject = configuredProject.UnconfiguredProject;
+
+#if VS2019
+            // Services is an interface in VS2017 and an abstract class in VS2019.
+            // Use reflection to bypass this difference, the rest of the fields are the same.
+            var servicesProperty = configuredProject.GetType().GetProperty("Services");
+            var services = servicesProperty.GetValue(configuredProject, null);
+
+            // Get to UserPropertiesProvider.GetCommonProperties().
+            var uppProperty = services.GetType().GetProperty("UserPropertiesProvider");
+            var upp = (IProjectPropertiesProvider)uppProperty.GetValue(services);
+            userProperties = upp.GetCommonProperties();
+
+            // Get to ProjectPropertiesProvider.GetCommonProperties().
+            var pppProperty = services.GetType().GetProperty("ProjectPropertiesProvider");
+            var ppp = (IProjectPropertiesProvider)pppProperty.GetValue(services);
+            projectProperties = ppp.GetCommonProperties();
+
+#elif VS2022
             userProperties =
                 configuredProject.Services.UserPropertiesProvider.GetCommonProperties();
             projectProperties =
                 configuredProject.Services.ProjectPropertiesProvider.GetCommonProperties();
+
+#else
+#error Unsupported Visual Studio version
+#endif
         }
 
         public Task<string> GetAbsoluteRootPathAsync()