Add dtype promotion of result in separable filter

[fzimmermann89]

Promotes the result depending on the data and
kernel dtype. Add tests for it

Fixes #341

[fzimmermann89]

I think this should fix the issue...

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
src/mrpro/algorithms/csm
iterative_walsh.py	15	1	93%	52
src/mrpro/algorithms/dcf
dcf_voronoi.py	53	4	92%	29, 62–63, 90
src/mrpro/algorithms/optimizers
adam.py	17	1	94%	78
src/mrpro/algorithms/reconstruction
DirectReconstruction.py	61	36	41%	66–71, 88–96, 108–110, 126–133, 147–158
Reconstruction.py	8	1	88%	34
src/mrpro/data
AcqInfo.py	123	2	98%	176, 214
CsmData.py	21	3	86%	28, 72–74
DcfData.py	37	2	95%	31, 79
IData.py	61	3	95%	138, 144, 148
IHeader.py	65	2	97%	90, 117
KHeader.py	161	12	93%	37, 139–143, 178, 228, 239, 246–247, 250, 257
KNoise.py	24	9	62%	53–66
MoveDataMixin.py	126	14	89%	28, 122, 138, 152–154, 215, 278, 292, 371, 391–392, 409–410
QData.py	32	1	97%	56
SpatialDimension.py	44	1	98%	78
TrajectoryDescription.py	14	1	93%	37
acq_filters.py	10	1	90%	61
src/mrpro/data/_kdata
KData.py	97	9	91%	121–122, 131, 139, 193–194, 229, 234–235
KDataRemoveOsMixin.py	29	2	93%	55, 57
KDataSelectMixin.py	20	2	90%	60, 76
KDataSplitMixin.py	48	3	94%	63, 93, 102
src/mrpro/data/traj_calculators
KTrajectoryCalculator.py	25	2	92%	37, 59
KTrajectoryIsmrmrd.py	13	2	85%	55, 64
KTrajectoryPulseq.py	29	1	97%	68
src/mrpro/operators
CartesianSamplingOp.py	50	9	82%	63–64, 69–70, 75–76, 102, 105, 128
ConstraintsOp.py	60	2	97%	60, 62
EndomorphOperator.py	51	2	96%	223, 227
FiniteDifferenceOp.py	27	2	93%	62, 127
FourierOp.py	77	1	99%	145
GridSamplingOp.py	122	9	93%	73–74, 83–84, 91–92, 95, 97, 99
LinearOperator.py	80	4	95%	46, 145, 265, 270
Operator.py	52	1	98%	35
SliceProjectionOp.py	166	8	95%	53, 60, 62, 68, 205, 226, 259, 299
ZeroPadOp.py	16	1	94%	44
src/mrpro/utils
Rotation.py	453	28	94%	58–66, 106, 283, 369, 371, 398, 453, 458, 461, 476, 493, 498, 642, 647, 650, 666, 670, 745, 747, 755–756, 996, 1078
filters.py	61	2	97%	57, 62
slice_profiles.py	45	6	87%	32, 48, 125–128, 161
sliding_window.py	34	1	97%	46
split_idx.py	10	2	80%	57, 61
zero_pad_or_crop.py	31	6	81%	40, 44, 68, 71, 74, 77
TOTAL	3296	199	94%

Tests	Skipped	Failures	Errors	Time
751	0 💤	0 ❌	0 🔥	1m 8s ⏱️

[koflera]

looks good to me