rfc: Should the 'Testable Registry' be moved into its own library?

The `IRegistry` and testable registry is a nice, isolated set of capabilities which may be useful for many others.

There is nothing stopping people using the `ComAdmin` library to grab the testing capabilities, and in fact this library is still a good place for them - it's not too much 'outside' the domain of COM admin.

But in the interests of modularity and easier extension for others in the future, we might want to consider extracting the registry code into its own library, I'll leave this issue to track suggestions and requests.

Review the IRegistry and testable registry capabilities within the ComAdmin library, along with how callers would use them independently. The issue is complete when the modularity question has a decided scope and the resulting library boundaries and migration requirements are documented.

Written by the indexing model from the issue text.