Temporary release pipeline just for dotnet 8 images.

[VpOfEngineering]

Based on our discussion, creating release pipelines for dotnet 8 images.

In the future, I see two paths for this.

1. We have individual release pipelines for every image
2. We have a variable passed in to the single .yml to specify if we are only releasing a single version / worker's images

For now, this will unblock us.

Process would be:

1. Create hotfix image
2. Tag (with builds for all language workers)
3. Push images to container repository (using publish-dotnet-8.yml)
4. Push to each stage (using publish-appservice-stage-dotnet-8.yml)

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