Upsample data above midplane to full grid assuming stellarator symmetry

[unalmis]

This would be useful for FFT's or integration over a subset of the volume as discussed in #1101 . Currently algorithms that rely on such computations are forced to compute on the full volume, which impacts performance (memory and speed). Once we have a utility like

def map2fullgrid(grid, data):
   """Return data computed on grid as if it were computed on full grid."""

We can just call this inside the compute functions rather than raising warnings that computations are incorrect for quantities that compute integrals over subsets of the volume in #1094 .

[dpanici]

Need to consider symmetry of the underlying data

[dpanici]

Could check if at theta=0, zeta=0 the value is zero, then it is sin sym, but I would prefer to manually specify the symmetry

[dpanici]

DESC/tests/test_axis_limits.py

Line 194 in 95612fa

# TODO: remove when boozer transform works with multiple surfaces