Superquadrics for tensor-valued fields

We should be able to implement visualization of symmetric and non-symmetric matrix fields via superquadrics (e.g. [1,2]) with moderate effort. For this we might need some changes to Makie.jl, where we start from `meshscatter` and implement a new shader to render out the superquadrics. The matrix field should be evaluated either at quadrature points or nodes.

[1] Schultz, T., & Kindlmann, G. L. (2010). Superquadric glyphs for symmetric second-order tensors. IEEE transactions on visualization and computer graphics, 16(6), 1595-1604.

[2] Kratz, A., Auer, C., Stommel, M., & Hotz, I. (2013, February). Visualization and analysis of second‐order tensors: Moving beyond the symmetric positive‐definite case. In Computer Graphics Forum (Vol. 32, No. 1, pp. 49-74). Oxford, UK: Blackwell Publishing Ltd.