Migrate `aspire-with-azure-functions` sample to Central Package Management (CPM)

[asilverman]

The aspire-with-azure-functions sample should adopt Central Package Management (CPM) to align with modern .NET best practices and provide a more maintainable, scalable project structure.

Sample:
https://github.com/dotnet/aspire-samples/tree/main/samples/aspire-with-azure-functions

Rationale

CPM has become the recommended approach for managing NuGet dependencies in multi-project C# solutions. Updating this sample would:

• Improve clarity for developers by modeling current best practices for Aspire workloads.
• Reduce duplication of package version declarations across projects.
• Simplify dependency upgrades by centralizing version management.
• Better represent production-grade architecture, where CPM is widely adopted.

Proposed Changes

1. Add a Directory.Packages.props file at the root of the sample folder.
2. Move all package version declarations for shared dependencies into the props file.
3. Update each project (AppHost, Azure Functions app, shared libraries, etc.) to use versionless <PackageReference> entries.
4. Validate that the sample builds and runs identically post-change.

Example Structure

samples/aspire-with-azure-functions/
  Directory.Packages.props
  AppHost/
  FunctionsApp/
  ...

Outcome

Updating the sample to use CPM will make it a stronger reference implementation for Aspire projects integrating Azure Functions, demonstrating how to model dependencies in a modern, maintainable way.

Happy to submit a PR if this change is accepted.

[DamianEdwards]

I see this was done last month. We initially decided not to use CPM in this repo due to there still being some things that don't support it well, e.g. dotnet new. We also wanted to ensure each sample is easy to individually copy out of this repo use standalone. Using CPM per sample isn't so bad as long as the sample is .NET-centric (i.e. it is adding .NET projects as resources to the AppHost) but I think we should be consistent in the repo. I've logged #1420 to track this.