Use resolved publish output for NativeAOT IlcCompileInput

[Copilot]

When RunILLink=true, NativeAOT could still compile @(IntermediateAssembly) instead of the post-ILLink main assembly from $(IntermediateLinkDir). This updates ComputeIlcCompileInputs to select the resolved publish item for the app assembly when available, while preserving the existing fallback for flows that do not populate it.

• Main change

  • ComputeIlcCompileInputs now matches the app’s main assembly by name against @(ResolvedFileToPublish) entries marked PostprocessAssembly=true.
  • When a match is found, IlcCompileInput uses that resolved item instead of @(IntermediateAssembly).

• Fallback behavior

  • If no matching resolved publish item exists, IlcCompileInput continues to use @(IntermediateAssembly).
  • This keeps the non-ILLink and non-publish paths unchanged.

• Matching behavior

  • The lookup is based on the IntermediateAssembly file name so the main assembly can be sourced from the linked output without requiring consumers to override IlcCompileInput.

<!-- Before -->
<ManagedBinary Include="@(IntermediateAssembly)" />

<!-- After: prefer the matching resolved publish item when present -->
<_ResolvedManagedBinary Include="@(ResolvedFileToPublish)"
                        Condition="'%(ResolvedFileToPublish.PostprocessAssembly)' == 'true' ..." />
<ManagedBinary Condition="'@(_ResolvedManagedBinary)' != ''" Include="@(_ResolvedManagedBinary)" />
<ManagedBinary Condition="'@(_ResolvedManagedBinary)' == ''" Include="@(IntermediateAssembly)" />

[dotnet-policy-service]

Tagging subscribers to this area: @agocke, @dotnet/illink
See info in area-owners.md if you want to be subscribed.