Add MOI.modify for multiple changes at once

[rafabench]

This is a follow-up from jump-dev/MathOptInterface.jl#1800
It significantly improved the performance of updates. Using the same code from the PR above:

julia> @btime update_parameters_multiple_times_with_single_change(num_variables, num_solves)
  9.115 s (255872 allocations: 2.81 GiB)

julia> @btime update_parameters_multiple_times_with_multiple_changes(num_variables, num_solves)
  2.522 ms (5800 allocations: 2.33 MiB)

Modifying multiple objective coefficients isn't available in GLPK

[codecov]

Codecov Report

Merging #216 (d203670) into master (670d2fa) will increase coverage by 0.18%.
The diff coverage is 95.65%.

@@            Coverage Diff             @@
##           master     #216      +/-   ##
==========================================
+ Coverage   80.61%   80.79%   +0.18%     
==========================================
  Files           8        8              
  Lines        1836     1859      +23     
==========================================
+ Hits         1480     1502      +22     
- Misses        356      357       +1     

Impacted Files	Coverage Δ
src/MOI_wrapper/MOI_wrapper.jl	87.33% <95.65%> (+0.18%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 670d2fa...d203670. Read the comment docs.

[odow]

@joaquimg merge once you've taken a look and are happy

[joaquimg]

looks good