Remove filter_constraints

[odow]

We should consider removing filter_constraints keyword and make a function that does a filtered copy instead.

MathOptInterface.jl/src/Utilities/copy.jl

Line 257 in 6f166a9

filter_constraints::Union{Nothing,Function} = nothing,

(and everywhere around there)

Or a layer that filters out things.

@blegat had something similar
https://github.com/lanl-ansi/Juniper.jl/blob/3a30ee5298d0dae426348da840c994eda901b985/src/filter.jl#L1-L76

Some use-cases:

• filter out VariableName and ConstraintName
• filter out Integer and ZeroOne constraints
• filter out constraints not in the IISS