Build HyperDimLinearizer compatible classes and methods for 3D

[nhvaughan]

Need to build methods to fill higher dimensional variables using Dan's HyperDimLinearizer class. Needs at least the following:

• [x] VariableBase à la VariableBase in PlotUtils/MAT
• [x] VariableHyperDFromConfig à la VariableFromConfig in CCQENu
• [x] GetVariableHyperDFromConfig (similarly)
• [x] HistHyperDWrapperMap? Could you just use the 1D methods? Needs to interact with a HyperD
• [x] Implementation of HyperD/Linearized hists in event loops and analyze code
• [x] Some config convention (maybe similar to how 2D is done)

[nhvaughan]

See hyperdim-3d-nhv feature branch.