fix(pipeline): copy appsettings.json to output directory

Pipeline.CreateBuilder resolves configuration files relative
to the output directory, not the working directory the old
generic host used, so CI failed with FileNotFoundException
before any module ran.

Author: thomhurst

EnumerableAsyncProcessor.Pipeline/EnumerableAsyncProcessor.Pipeline.csproj

@@ -13,4 +13,9 @@
       <PackageReference Include="ModularPipelines.Git" Version="3.2.8" />
     </ItemGroup>
 
+    <ItemGroup>
+      <!-- Pipeline.CreateBuilder resolves configuration relative to the output directory -->
+      <None Include="appsettings.json" CopyToOutputDirectory="PreserveNewest" />
+    </ItemGroup>
+
 </Project>