MInor updates for `evaltensor_J`

[talassio]

This branch fixed autoallocations inside evaltensor_J and also adds:

• 6 tests to the call-back evaltensor_J which checks params%extra and compares J and JT using params%fortran_Jacobian=options%fortran_Jacobian

• 2 loops in assignments to avoid auto-allocations (due to j(*))

• avoids recalculating the same value inside assignment loops (adds scalar v)

[codecov[bot]]

Codecov Report

Merging #101 (98206ca) into master (415d945) will increase coverage by 0.31%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #101      +/-   ##
==========================================
+ Coverage   82.48%   82.80%   +0.31%     
==========================================
  Files           6        6              
  Lines        3637     3640       +3     
==========================================
+ Hits         3000     3014      +14     
+ Misses        637      626      -11     

Impacted Files	Coverage Δ
libRALFit/src/ral_nlls_internal.f90	81.77% <100.00%> (+0.52%)	:arrow_up:

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