eps2 constants too small?

[jhale]

@garth-wells raised the issue about the size of the eps2 constant which is used in various geometry kernels as a tolerance.

https://github.com/FEniCS/dolfinx/blob/main/cpp/dolfinx/geometry/utils.cpp#L482

Are they too small?

[nate-sime]

If there's no significant performance hit it would be helpful for the user to be able to define all geometric tolerances. It's particularly frustrating for meshes with diverse length scales.