Appropriate Fence Tool callbacks in NVprof focused connector

[vlkale]

Need to put in Appropriate Fence Tool callbacks in NVprof focused connector (soon to be renamed NVTX_Focused_connector from #175).

The tool-induced fences should be filtered out (at runtime) when the tool callback is invoked.

This PR will also involve accomodating for a Kokkos Tools environment variable, KOKKOSTOOLS_GLOBALFENCES, which is read by this tool at runtime and allows a Kokkos Tools user to turn the global fences (fence for any tool in the Kokkos Tools set) on or off.