Implement .NET 8.0 devfile sample

[thepetk]

Which area is this user story related to?

/area registry

User Story

As a developer working with the devfile registry I want to have available an up-to-date dotnet sample, so that can be used as a basis for new projects (for example in OCP).

That said we need to create a new dotnet sample that will replace the existing one: https://github.com/devfile-samples/devfile-sample-dotnet60-basic

The new sample should be based on the dotnet 8.0 stack: https://registry.devfile.io/viewer/devfiles/community/dotnet80

Also the registry should be updated in order to include the new sample here: https://github.com/devfile/registry/blob/main/extraDevfileEntries.yaml

Acceptance Criteria

• A new devfile sample has been created based on the registry's .NET 8.0 stack
• The extraDevfileEntries.yaml has been updated