Set request: Box or HyperRectangle

[blegat]

struct Box{T}
    lower::Vector{T}
    upper::Vector{T}
end

which is a cartesian product if Interval{T} so lower and upper are allowed to have infinite values. This has been requested by @migarstka for a long time and once again in https://github.com/oxfordcontrol/COSMO.jl/pull/129#issuecomment-771536349 It is also often requested from people in control where it's common to work with hyper-rectangles.

We would also have the bridges:

• Box to Intervals (Bridges.Constraint.Scalarize)
• Interval to Box (Bridges.Constraint.Vectorize)
• Zeros, Nonnegatives and Nonpositives to Box (otherwise, it would be scalarized and then vectorized to many 1-dimension boxes ^^)
• Box to Nonnegatives and Nonpositives (otherwise, it would be scalarized to Interval then bridged to a GreaterThan and a LessThan and then vectorized and it's many small 1-dim constraints)

[odow]

SCS 3.0 supports the Box cone: https://www.cvxgrp.org/scs/api/cones.html#cones