Add `arggauss`

[codecov[bot]]

Codecov Report

Base: 99.87% // Head: 99.87% // Increases project coverage by +0.00% :tada:

Coverage data is based on head (0714099) compared to base (91ac8ce). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #230 +/- ## ======================================= Coverage 99.87% 99.87% ======================================= Files 766 769 +3 Lines 7011 7036 +25 ======================================= + Hits 7002 7027 +25 Misses 9 9 ``` | [Impacted Files](https://codecov.io/gh/JuliaSmoothOptimizers/OptimizationProblems.jl/pull/230?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers) | Coverage Δ | | |---|---|---| | [src/ADNLPProblems/argauss.jl](https://codecov.io/gh/JuliaSmoothOptimizers/OptimizationProblems.jl/pull/230/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers#diff-c3JjL0FETkxQUHJvYmxlbXMvYXJnYXVzcy5qbA==) | `100.00% <100.00%> (ø)` | | | [src/Meta/argauss.jl](https://codecov.io/gh/JuliaSmoothOptimizers/OptimizationProblems.jl/pull/230/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers#diff-c3JjL01ldGEvYXJnYXVzcy5qbA==) | `100.00% <100.00%> (ø)` | | | [src/PureJuMP/argauss.jl](https://codecov.io/gh/JuliaSmoothOptimizers/OptimizationProblems.jl/pull/230/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers#diff-c3JjL1B1cmVKdU1QL2FyZ2F1c3Muamw=) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=JuliaSmoothOptimizers)

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