api: add mul interp mode

[mloubout]

TODO:

This needs to be made optional as, while in some cases it leads to a better conditioned discrete system, the computational cost is prohibitive.

[codecov]

Codecov Report

❌ Patch coverage is 46.15385% with 28 lines in your changes missing coverage. Please review.
✅ Project coverage is 53.17%. Comparing base (a00cca8) to head (99fd21a).

Files with missing lines	Patch %	Lines
devito/finite_differences/differentiable.py	25.00%	25 Missing and 2 partials ⚠️
devito/finite_differences/derivative.py	50.00%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (a00cca8) and HEAD (99fd21a). Click for more details.

HEAD has 8 uploads less than BASE

Flag	BASE (a00cca8)	HEAD (99fd21a)
	18	10

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2788       +/-   ##
===========================================
- Coverage   83.01%   53.17%   -29.85%     
===========================================
  Files         248      248               
  Lines       50957    50992       +35     
  Branches     4489     4499       +10     
===========================================
- Hits        42303    27114    -15189     
- Misses       7883    22900    +15017     
- Partials      771      978      +207     

Flag	Coverage Δ
pytest-gpu-aomp-amdgpuX	68.44% <44.23%> (-0.06%)	⬇️
pytest-gpu-nvc-nvidiaX	68.97% <44.23%> (-0.06%)	⬇️

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