It will reduce the cost of getting the thread runtime device tracker,
and will have a better runtime overhead if user constructs a lot of
short lived threads that use VTK-m.
Sandia National Laboratories recently changed management from the
Sandia Corporation to the National Technology & Engineering Solutions
of Sandia, LLC (NTESS). The copyright statements need to be updated
accordingly.
This allows code to include the RuntimeDeviceTracker without depending
on the device-specific adapters (I think).
Also changed the implementation to use a shared_ptr for the state so you
can pass it around and share the state easier.
