Add C and Fortran interfaces

[amontoison]

close #329

The PR enables the compilation of SMC.jl as a "standalone" shared library that can be called from C or Fortran.
The implementation of the interfaces is highly based on what was done in Krylov.jl.

The PR contains new C, Fortran and Julia tests.
The Julia tests are directly on the @ccallable, which is quite different to what we do in SMC.jl.
A few C / Fortran examples are also provided.

We will probably need to discuss about the C API and what we want to expose but let's first see if the current CI tests for the "proof-of-concept" are passing.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.20%. Comparing base (f177507) to head (2484fdb).

Additional details and impacted files

@@               Coverage Diff               @@
##           c_interface     #341      +/-   ##
===============================================
+ Coverage        97.61%   99.20%   +1.59%     
===============================================
  Files               21       21              
  Lines             2219     2151      -68     
===============================================
- Hits              2166     2134      -32     
+ Misses              53       17      -36     

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[amontoison]

@gdalle @adrhill
The C and Fortran tests passed on all platforms 🎉 https://github.com/JuliaDiff/SparseMatrixColorings.jl/actions/runs/33947638484?pr=341

I need to polish and simplify the code, without AI, such that it can be read by anyone.
I will convert the PR to draft until it's clean enough for a review.