Add new constructors for mixed models

[tmigot]

• Need more unit tests to cover ADNLSModel(...)
• up doc

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.06% 🎉

Comparison is base (515bcf3) 95.12% compared to head (0c8fc6a) 95.18%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #202      +/-   ##
==========================================
+ Coverage   95.12%   95.18%   +0.06%     
==========================================
  Files          14       14              
  Lines        1621     1642      +21     
==========================================
+ Hits         1542     1563      +21     
  Misses         79       79              

Files Changed	Coverage Δ
src/nlp.jl	99.22% <ø> (ø)
src/nls.jl	98.87% <ø> (ø)
src/ADNLPModels.jl	100.00% <100.00%> (ø)

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[github-actions]

Package name	latest	stable
CaNNOLeS.jl
DCISolver.jl
DerivativeFreeSolvers.jl
JSOSolvers.jl
NLPModelsIpopt.jl
OptimizationProblems.jl
Percival.jl
QuadraticModels.jl
SolverBenchmark.jl
SolverTools.jl