All raw FXI data is now nested
All raw FXI data is now nested

Hardwiring for now, we are only interested in FXI right now and the
raw data is nested to support derived data and other things.

Signed-off-by: Marcus D. Hanwell <09f3a87217880bd167b70879e4c1906a3ba98bd2@bnl.gov>

OpenChemistry/tomviz,OpenChemistry/tomviz,OpenChemistry/tomviz,OpenChemistry/tomviz