[release/5.0] Include CrossOs diagnostic assets for signing (#41660)

* Include CrossOs diagnostic assets for signing

* Update eng/Signing.props

Co-authored-by: Santiago Fernandez Madero <safern@microsoft.com>

* Only glob the symbol package for CrossOS diagnostics

Co-authored-by: Juan Sebastian Hoyos Ayala <juhoyosa@microsoft.com>
Co-authored-by: Juan Hoyos <juan.hoyos@microsoft.com>
Co-authored-by: Santiago Fernandez Madero <safern@microsoft.com>

Author: 3 people

eng/Signing.props

@@ -111,6 +111,11 @@
       <DownloadedSymbolPackages Include="$(DownloadDirectory)**\*.symbols.nupkg" />
       <ItemsToSign Include="$(DownloadDirectory)**\*.nupkg" Exclude="@(DownloadedSymbolPackages)" />
 
+      <!-- The cross OS diagnostics symbol packages need to be signed as they are the only packages
+      that have a specific version of assets that are only meant to be indexed in symbol servers.
+      Since only *symbols.nupkg get indexed, and installer doesn't produce these, we need to glob them for signing. -->
+      <ItemsToSign Include="$(DownloadDirectory)**\*CrossOsDiag*.symbols.nupkg" />
+
       <ItemsToSign Include="$(DownloadDirectory)**\*.deb" />
       <ItemsToSign Include="$(DownloadDirectory)**\*.rpm" />
     </ItemGroup>