Promote abstol and reltol type to match eltype(A)

[ma-sadeghi]

Fixes #396

[codecov[bot]]

Codecov Report

Merging #397 (4c77e2c) into main (f4f6940) will decrease coverage by 0.93%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #397      +/-   ##
==========================================
- Coverage   68.97%   68.04%   -0.93%     
==========================================
  Files          26       26              
  Lines        1905     1906       +1     
==========================================
- Hits         1314     1297      -17     
- Misses        591      609      +18     

Files	Coverage Δ
src/common.jl	89.28% <100.00%> (-1.46%)	:arrow_down:

... and 6 files with indirect coverage changes

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[ma-sadeghi]

@ChrisRackauckas Should we change here as well? (to prob.b)

https://github.com/SciML/LinearSolve.jl/blob/f4f69409250ee359bb26e1409d56d53ca3d53e29/src/common.jl#L118-L119

[ChrisRackauckas]

yes that would be good to change.

[amontoison]

It will not work if the linear systems have complex numbers. You need real(eltype(b)) here.