Support closing of a LockResource by a different thread

The LockManager currently only allows closing (unlocking) a previously claimed lock by the same thread.

A useful/needed improvement is to allow handing the LockResource to a different thread (for example a background scheduler) to close (unlock) the resource after finishing a specific task.

This will be implemented by simply allowing the LockResource#close() to be invoked by another thread. Then, the LockResource instance itself can be 'shared' as the 'handle' to do this.