Add DataFrames.jl extension

[odow]

Take II of #3441
x-ref #3438

TODOs

• Add documentation to extension
• Rework existing tutorials to leverage new syntax

See https://jump.dev/JuMP.jl/previews/PR3821/extensions/DataFrames/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.92%. Comparing base (9fb707c) to head (890ede8).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3821      +/-   ##
==========================================
+ Coverage   97.90%   97.92%   +0.01%     
==========================================
  Files          44       46       +2     
  Lines        6022     6077      +55     
==========================================
+ Hits         5896     5951      +55     
  Misses        126      126              

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[odow]

Is this an improvement? I'm not sure.

Now: https://jump.dev/JuMP.jl/previews/PR3821/tutorials/linear/multi/
Previous: https://jump.dev/JuMP.jl/stable/tutorials/linear/multi/

[blegat]

We could also have an array with the same syntax as SparseAxisArray and a DataFrame instead of a Dict as a backend.
I guess we could also have both the container of your PR and the one I just suggested.