Perform `klu` in `init_cacheval`

[rayegun]

Let's see if this solves our problem. It simplifies things, and reaches into internal functions less. I'll investigate UMFPACK as well, I don't remember why we're reaching so deep into that package instead of just running the factorization in init_cacheval.

[codecov[bot]]

Codecov Report

Merging #158 (3342625) into main (c5168f3) will increase coverage by 0.47%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #158      +/-   ##
==========================================
+ Coverage   65.66%   66.13%   +0.47%     
==========================================
  Files           9        9              
  Lines         632      629       -3     
==========================================
+ Hits          415      416       +1     
+ Misses        217      213       -4     

Impacted Files	Coverage Δ
src/factorization.jl	78.84% <100.00%> (+1.59%)	:arrow_up:

:mega: Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[rayegun]

Uh what's happening with codecov? There's no way these changes should do this.