Conditionally import shared project in build process

Added a condition to skip importing the shared project in `Plugin-Shared.shproj` if `SkipSharedProject` is true. Updated the GitHub Actions workflow to set this property when building the solution.

Author: ivandrofly

.github/workflows/main.yml

@@ -31,7 +31,7 @@ jobs:
 
       # Build the solution
       - name: Build solution
-        run: msbuild "source\Plugins.sln" /p:Configuration=Release /p:BuildProjectReferences=false
+        run: msbuild "source\Plugins.sln" /p:Configuration=Release /p:SkipSharedProject=true
 
           # Run tests (optional)
           #- name: Run tests

source/Plugin-Shared/Plugin-Shared.shproj

@@ -8,6 +8,6 @@
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.Common.Default.props" />
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.Common.props" />
   <PropertyGroup />
-  <Import Project="Plugin-Shared.projitems" Label="Shared" />
+  <Import Project="Plugin-Shared.projitems" Label="Shared" Condition="'$(SkipSharedProject)' != 'true'"/>
   <Import Project="$(MSBuildExtensionsPath32)\Microsoft\VisualStudio\v$(VisualStudioVersion)\CodeSharing\Microsoft.CodeSharing.CSharp.targets" />
 </Project>