[WIP] Simple JFNK

[avik-pal]

I was playing around with JNFK for DEQs and the Nonlinear Solve implementation is a bit too complicated for those purposes

• Working Version
  • Batched Version
• Testing
• Are we okay with LinearSolve.jl as a dependency? -- Not really, let's use Krylov.jl directly as an extension
• Preconditioners

[codecov]

Codecov Report

Merging #83 (9858095) into main (1600f7c) will decrease coverage by 92.76%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #83       +/-   ##
==========================================
- Coverage   92.94%   0.19%   -92.76%     
==========================================
  Files          21      21               
  Lines        1049    1046        -3     
==========================================
- Hits          975       2      -973     
- Misses         74    1044      +970     

Files	Coverage Δ
src/raphson.jl	0.00% <ø> (-90.00%)	⬇️
ext/SimpleNonlinearSolveNNlibExt.jl	0.00% <0.00%> (-90.25%)	⬇️
src/SimpleNonlinearSolve.jl	40.00% <0.00%> (-60.00%)	⬇️
src/broyden.jl	0.00% <0.00%> (-92.11%)	⬇️
src/jnfk.jl	0.00% <0.00%> (ø)

... and 17 files with indirect coverage changes

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