[Sample App] Add Microsoft.Extensions.Http.Resilience

[brminnick]

Description of Change

This PR replaces Microsoft.Extensions.Http.Polly with Microsoft.Extensions.Http.Resilience.

In .NET 8, Microsoft teamed up with the App-vNext.Polly team to create a more-performant version of Polly. The new Microsoft.Extensions.Http.Resilience library uses the new, more performant version of Polly.

Meanwhile [Microsoft.Extensions.Http.Polly](https://www.nuget.org/packages/Microsoft.Extensions.Http.Polly) uses the older, less performant, version of Polly now rebranded as Polly.Core.

To ensure our Sample App adheres to best practices recommended for all .NET MAUI developers, we are upgrading Microsoft.Extensions.Http.Polly with Microsoft.Extensions.Http.Resilience.

PR Checklist

• Has samples (if omitted, state reason in description)
• Rebased on top of main at time of PR
• Changes adhere to coding standard

Additional information

More information is available in this .NET Blog Post:

https://devblogs.microsoft.com/dotnet/building-resilient-cloud-services-with-dotnet-8/

Resilience packages

• Microsoft.Extensions.Resilience: This package provides a minimal set of APIs. Its primary purpose is to enrich Polly’s metrics using the AddResilienceEnricher extension for IServiceCollection. For more details, refer to the Resilience docs.
• Microsoft.Extensions.Http.Resilience: This package offers HTTP-specific APIs that integrate with Polly v8 and IHttpClientFactory. It is the successor to the Microsoft.Extensions.Http.Polly package and is recommended for all new projects. See the section below for more information.
• Microsoft.Extensions.Http.Polly: This package integrates older versions of Polly with HttpClient and IHttpClientFactory.