Try to get things working on Julia 1.5

[tkoolen]

• Requires MOI master, jump-dev/MathOptInterface.jl@f71ed83 (ran into an ambiguity issue that I think Small simplification for adding SingleVariable constraints jump-dev/MathOptInterface.jl#1096 fixed)
• Requires Symmetrize -> upper triangularize in copy from ModelLike osqp/OSQP.jl#90
• FunctionWrappers quick fix is now unusable. Unfortunately, the actual FunctionWrappers is still as broken as ever (or rather cfunction?). Worked around by simply disabling function wrapping for now (at a performance/allocation penalty).
• I don't have a Gurobi license anymore, so I replaced it with SCIP, which is now easy to install on OSX and Linux.
• GLPK seems pretty broken, so replaced it with Cbc.
• Marked a whole bunch of allocation tests broken; likely due to differences in the way allocations are measured post simplify @allocated macro JuliaLang/julia#33717.

That said, this passes tests locally.