Improve interface

[BatyLeo]

• New maximizer_kwargs method to get the keyword arguments for the maximizer in each benchmark
• More flexible objective_value method

[codecov]

Codecov Report

Attention: Patch coverage is 85.71429% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/Utils/interface.jl	84.61%	2 Missing ⚠️

Files with missing lines	Coverage Δ
src/DecisionFocusedLearningBenchmarks.jl	100.00% <ø> (ø)
src/Utils/data_sample.jl	100.00% <100.00%> (ø)
src/Utils/interface.jl	90.47% <84.61%> (-9.53%)	⬇️