Adding support for btens to multi_shell_fiber_response function

[karanphil]

Hi!

This is a really small modification of reconst.mcsd.multi_shell_fiber_response , adding support for the b-tensor (btens) option. I used the new implementation of btens in gradient_table and single_tensor, so that the reconst.mcsd.multi_shell_fiber_response function now returns the response function according to the b-tensor shape of each inputed b-value. For example, I use this for multi-encoding msmt-CSD (see my paper for more details https://doi.org/10.1016/j.media.2022.102476) on Scilpy (I am a PhD student supervised by Maxime Descoteaux), and I had this version of the function in my code. It runs as usual when no btens is given, by setting every b-value as LTE (linear tensor encoding).

It would be very appreciated if this could go in the next release. @gabknight

[skoudoro]

Hi @karanphil,

Thank you for this. As usual, can you add some basic test?

It can go to the next release if @RafaelNH or @arokem find time to review it.

[codecov]

Codecov Report

Merging #2956 (277fb83) into master (09e7231) will decrease coverage by 0.01%.
The diff coverage is 62.50%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2956      +/-   ##
==========================================
- Coverage   81.79%   81.78%   -0.01%     
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  Files         146      146              
  Lines       20401    20406       +5     
  Branches     3238     3240       +2     
==========================================
+ Hits        16686    16689       +3     
- Misses       2898     2900       +2     
  Partials      817      817              

Files	Coverage Δ
dipy/reconst/mcsd.py	86.11% <62.50%> (-0.82%)	⬇️

... and 1 file with indirect coverage changes

[skoudoro]

@RafaelNH or @arokem, Do you have any opinions concerning this PR?

[arokem]

LGTM! I think we can merge this

[arnaudbore]

@skoudoro I think you can merge this one easily since @arokem approved it 👍