(At any future breaking change) Move Microsoft.IdentityModel.Tokens out of shared assembly space

https://github.com/Azure/azure-functions-host/issues/8889 covers what we should do for current versions of the host, but if we have an opportunity for a breaking change, it would be best to stop having the host attempt to share this assembly with user code at all - it leads to errors like we see in https://github.com/Azure/azure-functions-host/issues/7878.

We could move to a private assembly if there are no shared types which the host might pass forward. Alternatively, we could move any piece leveraging this into an extension so that it becomes owned in full by the application payload. It might even be possible to completely remove the dependency from the host.

This is considered a breaking change because applications may be relying on the host providing this assembly. As such, we should only take this on if a major version change were to occur.

No source files, tests, or entry points are named. Start by tracing the host's Microsoft.IdentityModel.Tokens dependency and reviewing issues 8889 and 7878; done means implementing a selected breaking-change approach for ownership of that assembly or removing the dependency.

Written by the indexing model from the issue text.