ReshapedArrays support

[gdalle]

Fix #770

[gdalle]

Still a draft cause i want to see if I can preserve sparsity

[gdalle]

Actually it makes no sense to preserve sparsity

[codecov]

Codecov Report

Attention: Patch coverage is 97.78339% with 114 lines in your changes missing coverage. Please review.

Project coverage is 98.26%. Comparing base (8035437) to head (1d33fb6).
Report is 270 commits behind head on main.

Files with missing lines	Patch %	Lines
src/cr.jl	70.04%	68 Missing ⚠️
src/krylov_utils.jl	91.00%	17 Missing ⚠️
src/lslq.jl	96.41%	8 Missing ⚠️
src/craigmr.jl	95.54%	7 Missing ⚠️
src/lsmr.jl	97.58%	5 Missing ⚠️
src/lsqr.jl	97.39%	5 Missing ⚠️
src/craig.jl	98.69%	2 Missing ⚠️
src/krylov_solvers.jl	99.86%	1 Missing ⚠️
src/lnlq.jl	99.54%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #771      +/-   ##
==========================================
+ Coverage   97.98%   98.26%   +0.28%     
==========================================
  Files          37       39       +2     
  Lines        6091     7107    +1016     
==========================================
+ Hits         5968     6984    +1016     
  Misses        123      123              

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[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCISolver.jl
FletcherPenaltySolver.jl
JSOSolvers.jl
LLSModels.jl
LinearSolve.jl
Percival.jl
RipQP.jl

[amontoison]

@gdalle May I ask you to rebase your PR?
I didn't know that you opened a PR about the ReshapedArrays support.

Is it still relevant?

[gdalle]

I don't even remember why I needed it anymore, it's probably from the time where ImplicitDifferentiation would do a lot of reshaping. Now it only accepts vectors so that's easier. Let's close this, I'll reopen if the need arises.