[Don't Merge] Add Enlsip

[avik-pal]

Doens't quite work. Enlsip needs a constraint, so I added a dummy constraint but this doesn't seem to work correctly.

Fixes #433

[codecov]

Codecov Report

Attention: Patch coverage is 7.50000% with 37 lines in your changes are missing coverage. Please review.

Project coverage is 78.87%. Comparing base (411f7d3) to head (d719ee3).

Files	Patch %	Lines
ext/NonlinearSolveEnlsipExt.jl	0.00%	32 Missing ⚠️
src/algorithms/extension_algs.jl	0.00%	4 Missing ⚠️
src/utils.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #436      +/-   ##
==========================================
- Coverage   86.46%   78.87%   -7.60%     
==========================================
  Files          47       48       +1     
  Lines        2904     2939      +35     
==========================================
- Hits         2511     2318     -193     
- Misses        393      621     +228     

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