Use Root scope when current is null (fixes #646)

[ltines]

Fixes #646 by using Root scope when current scope in ExtensionContainerScopeCache.current is null. This can happen when WindsorScopedServiceProvider is called from a new thread (or rather different async context).

In this situation ForcedScope uses the original root scope. It also restores it as ExtensionContainerScopeCache.current on dispose.

The only case that I haven't figured out is when resolving directly via IWindsorContainer (and not through IServiceProvider) on a new thread. ExtensionContainerScopeAccessor.GetScope still throws "No scope available"

[alkampfergit]

I still ask to check for our pr #668 that will fix this and also add support for .NET 8 keyed services. If it is possible could you check code of pr #668 to verify if this fixes null scope in your situation? I'm asking because the support for .NET 8 branch is opened from a long time and I'd like it to be closed if possible (we are in production with that version using a private package source and I'd really like to move again on supported nuget packages)

[ltines]

@alkampfergit i had a quick look, but need to read a lot about semantics (especially keyed / not keyed). I would like to implement it using named instances in Castle so we don't have to introduce new concepts.

[alkampfergit]

Remember that if you are moving to dependency injection version 8.0.0 without keyed service support the adapter does not works . The problem presents when any library starts using keyed service and new resolution semantic, so you got weird error.