Add Free Boundary Capability

[dpanici]

The most useful part of this repo for myself would be to have a nice, self-contained way to obtain the necessary information for a free boundary equilibrium based off of an EFIT gfile (or alternatively, a DIIID shot number and timeslice). This requires

• Capability to read an EFIT gfile and extract the necessary boundary (as initial guess), profile and enclosed flux information
• Inclusion of a nominal coilset, to be used for free-boundary
• inclusion of an interface with the MDS trees in order to extract the currents for a given shot.
  • mdsthin could be a possible way
• a function then that can generate the DESC coils object, base fixed bdry eq and the script for running free-boundary DESC