Add gap metrics and visualization

[SBlokhuizen]

Still in draft...

• Calculates and adds metrics of clearance gaps for WEST (e.g. UROG, EROG, etc) and ITER, according to the DINA conventions (g1, g2, g4, g5, Rmin, Rmax).
  • The gap metrics are shown both for the resulting equilibrium from NICE, as well as for the desired shape input.
• Added visualization to interactively view the gap reference points, target positions, gap distances, and gap information on hover.
• Added option for setting gaps using the machine-specific default gaps for WEST and ITER, so users don't have to supply their own equilibrium IDS to configure the gaps.
• Enabled warm start for nice direct mode by default