Reorganize the utils

[mishapadidar]

The utils directory has started to accumulate some clutter. In particular, there are three files which could be moved, or be broken apart and integrated with Simsopt: permanent_magnet_helper_functions.py, polarization_project.py, famus_helpers.py

The three files all add tools related to permanent magnets.

• Many of the tools in permanent_magnet_helper_functions.py could be removed or move altogether, since they are not directly related to permanent magnets. For example, make_qfm makes a QFM surface.
• famus_helpers.py is intended to ease the use of FAMUS with Simsopt. As suggested by @akaptano, Simsopt could perform the FAMUS optimization internally after adding a couple new functions.
• polarization_project.py adds methods for creating permanent magnet grids with special polarization directions. @akaptano suggests this could be massaged into geo