Use Artifacts Output

Use .NET 8 Artifacts Output feature to put all build output in a central directory structure instead of in each project directory.

Author: martincostello

.gitignore

@@ -17,6 +17,7 @@
 mono_crash.*
 
 # Build results
+[Aa]rtifacts/
 [Bb]uild/
 [Dd]ebug/
 [Dd]ebugPublic/

Directory.Build.props

@@ -21,6 +21,7 @@
     <RepositoryUrl>https://github.com/grafana/grafana-opentelemetry-dotnet</RepositoryUrl>
     <SymbolPackageFormat>snupkg</SymbolPackageFormat>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <UseArtifactsOutput>true</UseArtifactsOutput>
   </PropertyGroup>
   <ItemGroup>
     <None Include="$(MSBuildThisFileDirectory)/internal/img/$(PackageIcon)" Pack="True" PackagePath="" />