Add the ability for static lifetime store to be explicitly cleared

[ChrisGuzak]

in the case of a Win32 service that uses the static lifetime store (using static_lifetime) we need to respond to the service shutdown request and un-register our factories. to do this we need to be able to clear the entry in the static lifetime store

[kennykerr]

The static lifetime store is designed to clear itself when the last apartment is torn down. Is this not working?

[oldnewthing]

The issue here is a shared service. One service needs to clean up all its COM objects, but other services are still using COM. I am working on a PR to address this specific scenario.