Add SvdWork, merge lax::SVD_ into Lapack trait

[termoshtt]

Same as #340, #341, #343 for #168

[codecov]

Codecov Report

Merging #345 (d75c693) into master (b74552e) will increase coverage by 0.62%.
The diff coverage is 98.40%.

@@            Coverage Diff             @@
##           master     #345      +/-   ##
==========================================
+ Coverage   89.42%   90.05%   +0.62%     
==========================================
  Files          74       74              
  Lines        4238     4525     +287     
==========================================
+ Hits         3790     4075     +285     
- Misses        448      450       +2     

Impacted Files	Coverage Δ
ndarray-linalg/src/least_squares.rs	96.15% <0.00%> (ø)
lax/src/svd.rs	97.35% <96.85%> (+1.27%)	⬆️
lax/src/least_squares.rs	100.00% <100.00%> (ø)
lax/src/lib.rs	100.00% <100.00%> (ø)
lax/src/svddc.rs	100.00% <100.00%> (ø)

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