Add model_from

[blegat]

One target use case would be to allow to easily create JuMP from matrix input with https://github.com/JuliaOpt/MatrixOptInterface.jl/tree/master/src, e.g. to replace MathProgBase's linprog.
For instance:

using JuMP, MatrixOptInterface
model = model_from(LPStandardForm(MOI.MAX_SENSE, c, A, b))
set_optimizer(model, GLPK.Optimizer)
optimize!(model)
sol = value.(all_variables(model))

[codecov]

Codecov Report

Merging #2245 into master will increase coverage by 0.36%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2245      +/-   ##
==========================================
+ Coverage   91.27%   91.63%   +0.36%     
==========================================
  Files          42       42              
  Lines        4184     4425     +241     
==========================================
+ Hits         3819     4055     +236     
- Misses        365      370       +5     

Impacted Files	Coverage Δ
src/file_formats.jl	100.00% <100.00%> (ø)
src/macros.jl	94.47% <0.00%> (+1.95%)	⬆️

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[odow]

I don't understand the need for this?

It's a function to save two lines. Shouldn't this be something copy_to, if it exists at all?

[blegat]

I thought it would be more complicated when I started this. It might obscure things more than help. Still I thought it might be worth discussing whether we want something like this as it might be a quite common operation.

[odow]

This is either a documentation issue if MOI.copy_to, or a possible need for an exported JuMP.copy_to.

[odow]

Can this be closed? I don't see the value in adding an extra function to save two lines.