Changing stencils as they approach domain edges

This creates a struct called NeboVaryingEdgeStencilOneDim and NeboVaryingEdgeStencilBuilder that creates a single stencil which morphs into another stencil depending on how close to a domain edge it is evaluating at. It takes in a main stencil, and then a list of stencils to execute on the negative side of a field as it closes in on a domain edge, and another list of stencils to execute on the positive side of a field as it closes in on a domain edge. A domain edge is represented by a boundary condition in Nebo.

This struct does not work properly if used in a Nebo reduction or if used in a NeboBoundaryConditionBuilder.