[REQ][ASPNET] Create .NET 8 (or 10) ASP.NET server template

Is your feature request related to a problem? Please describe.

The ASP.NET server generation is old and outdated. The available project templates and README are no longer up to date, and official Docker images for recent .NET versions do not exist.

Describe the solution you'd like

A new generator template for ASP.NET targeting .NET 8 should be created. If there are concerns about breaking changes, default to .NET 10. The solution should provide:

• Up-to-date project scaffolding for modern .NET (8 and/or 10)
• An updated README (whatever is auto-generated is fine)
• Official Docker images

This will help reduce confusion and manual workaround requirements for consumers who need/want modern .NET support.

Describe alternatives you've considered

• Using other generators/tools, such as swagger-gen
• Manually updating generated files

Additional context

I'd like to use .NET 8 as a baseline, but if breaking changes are an issue, we can start with .NET 10.

I'm willing to create a PR.

UPDATE:
Ah, determineTemplateVersion() provides an easy switch for how to handle .NET 8 (old or new template).
We also want to add 9.0 and 10.0 as valid values of aspnetCoreVersion.

I think I would create a 10.0 template to be the most modern and if .NET 9 works with it, great! If not, it can use the old one. .NET 8 and 9 go out of support in November, so we don't need to be overly concerned about those.

Beginne damit, determineTemplateVersion() und die Verarbeitung von aspnetCoreVersion zu finden; untersuche anschließend das vorhandene ASP.NET-Server-Template sowie dessen README und Docker-Konfiguration. Als erledigt gilt die Aufgabe, wenn konsistent ein modernes Template für .NET 8, .NET 9 oder .NET 10 ausgewählt wird, unterstützte Versionswerte funktionieren, die README aktuell ist und offizielle Docker-Images bereitgestellt werden.