Upgrade WebJobHelloWorld sample to .NET 8

[Copilot]

This PR updates the WebJobHelloWorld sample to use modern .NET 8 patterns and latest stable packages.

Changes include:

• Updated target framework from netcoreapp2.2 to net8.0
• Updated all package references to their latest stable versions:
  • Microsoft.Azure.WebJobs: 3.0.41
  • Microsoft.Azure.WebJobs.Extensions: 5.0.0
  • Microsoft.Azure.WebJobs.Extensions.Storage.Queues: 5.3.0
  • Microsoft.Extensions.Configuration.AzureAppConfiguration: 8.0.0
  • Microsoft.Extensions.Logging: 8.0.0
  • Microsoft.Extensions.Logging.Console: 8.0.0
• Modernized code with file-scoped namespaces
• Updated WebJobs configuration to use the modern hosting pattern
• Added ImplicitUsings and Nullable support to the project
• Added a README.md with documentation on how to use the sample

The sample now follows best practices for WebJob applications in .NET 8.

Fixes #1060.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• cdn.fwupd.org
  • Triggering command: /usr/bin/fwupdmgr refresh (dns block)
• crl3.digicert.com
  • Triggering command: dotnet build (dns block)
• crl4.digicert.com
  • Triggering command: dotnet build (dns block)
• ocsp.digicert.com
  • Triggering command: dotnet build (dns block)
• s.symcb.com
  • Triggering command: dotnet build (dns block)
• s.symcd.com
  • Triggering command: dotnet build (dns block)
• ts-crl.ws.symantec.com
  • Triggering command: dotnet build (dns block)
• ts-ocsp.ws.symantec.com
  • Triggering command: dotnet build (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.