Density-likes should not be wrangler-global

[inducer]

Specifically, this code here:

boxtree/boxtree/pyfmmlib_integration.py

Lines 379 to 394 in d48fcdf

	# FIXME: dipole_vec shouldn't be stored here! Otherwise, we'll recompute
	# bunches of tree-dependent stuff for every new dipole vector.
	# It's not super bad because the dipole vectors are typically geometry
	# normals and thus change about at the same time as the tree... but there's
	# still no reason for them to be here.
	self.use_dipoles = dipole_vec is not None
	if self.use_dipoles:
	assert dipole_vec.shape == (self.dim, self.tree.nsources)
	if not dipoles_already_reordered:
	dipole_vec = self.reorder_sources(dipole_vec)
	self.dipole_vec = dipole_vec.copy(order="F")
	else:
	self.dipole_vec = None

should not exist.

cc @gaohao95

[inducer]

It turns out that source arguments are wrangler-global in sumpy as well:

https://github.com/inducer/sumpy/blob/e1048b0a4c0c8512d0765e4eef09963dcc77ab0f/sumpy/fmm.py#L314

So both need to change.

[inducer]

So the way that this should go IMO is that we need to change the drive_fmm interface to take in a dictionary (containing densities, and, if needed, dipole vectors and other per-source arguments).