Merge `Solve_`, `Solveh_` and `Cholesky_` into `Lapack` trait

[termoshtt]

For #168, Same as #340, #341, #343, and #345

• Merge Solve_ into Lapack trait
  • Add InvWork struct
• Merge Solveh_ into Lapack trait
  • Add BkWork struct
• Merge Cholesky_ into Lapack trait

[codecov[bot]]

Codecov Report

Merging #346 (7e61539) into master (07ab31d) will decrease coverage by 0.06%. The diff coverage is 85.33%.

@@            Coverage Diff             @@
##           master     #346      +/-   ##
==========================================
- Coverage   90.05%   89.98%   -0.07%     
==========================================
  Files          74       74              
  Lines        4525     4555      +30     
==========================================
+ Hits         4075     4099      +24     
- Misses        450      456       +6     

Impacted Files	Coverage Δ
lax/src/cholesky.rs	100.00% <ø> (ø)
lax/src/solveh.rs	73.21% <72.41%> (-2.30%)	:arrow_down:
lax/src/lib.rs	94.64% <86.36%> (-5.36%)	:arrow_down:
lax/src/solve.rs	100.00% <100.00%> (ø)

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