Support Azure Functions Isolated Model with .NET 8.

[mcollier]

This issue is for a: (mark with an x)

- [ ] bug report -> please search issues before submitting
- [x] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)

Minimal steps to reproduce

Support Azure Functions isolated model with .NET 8.

Mention any other details that might be useful

• The Isolated model is the long-term plan per https://techcommunity.microsoft.com/t5/apps-on-azure-blog/net-on-azure-functions-august-2023-roadmap-update/ba-p/3910098.
• Isolated model language support.