Add boundary condition type to repr for surfaces

[MicahGale]

Is your feature request related to a problem? Please describe.

It would be helpful sometimes to see the boundary condition state (e.g., is_reflective, is_white_boundary), and there's no easy way to get that from repr(surface).

Describe the solution you'd like

I would like is_reflective: True, or something similar to show in repr(surface)

Describe alternatives you've considered
Users just have to print(surface.is_reflecting)