`aspire run` for file-based AppHost doesn't rebuild project references

I've observed when using a file-based AppHost that referenced projects aren't rebuilt on changes. The issue seems to repro when `dotnet run apphost.cs` is used so it might not be specific to the Aspire CLI.

I am able to workaround this by manually building referenced projects via `dotnet build` before calling `aspire run`.

Reproduce the issue with a file-based AppHost using both `dotnet run apphost.cs` and `aspire run`, then trace how referenced projects are detected and rebuilt. It is done when changes to referenced projects are rebuilt automatically without a separate `dotnet build`.

Written by the indexing model from the issue text.