Rigid body boundary condition from element specified to node/sideset specified

[hovey]

Hi @tripaanu (cc to RMU team @carlsenrw @CompMechPitt @wangyrmu )

Currently, the rigid body boundary condition on the brain exterior in ABAQUS is implemented on a per-element basis, meaning that all nodes connected to that element experience rigid body rotation. This is a bit less precise that we should be. Instead, only the exterior nodes on the exterior elements should be rotating rigidly. The exterior nodes are available either from the nodeset or sideset.

Documentation reference:

https://github.com/autotwin/mesh/tree/main/doc/T1_Utah_SCI_brain#simulations