Add tests in proteus.mbd

[tridelat]

Tests to add for proteus.mbd (FSI):

• [ ] moments/forces retrieved from NS (update barycenters directly in RANS2P/RANS3P or check that moment calculations are right)
• [ ] added-mass matrix in local coordinates (e.g. rotate body with "inifinitely" far domain boundaries and check that matrix is the same)
• [ ] add simple and cheap floating/submerged body case as a test