solver benchmark: specifying solver-specific options

[arnavk23]

Updates to tutorial
docs: add "Handling solver_specific in benchmark runs" section toindex.jmd with explanation, notes, and a short conceptual example showing how to pass solver-specific options to benchmark calls.

• Tutorial name: introduction-to-solverbenchmark
• Confirm that either:
  • There is an issue for this tutorial:
    • Add documentation on solver_specific in benchmark SolverBenchmark.jl#152
  • It was discussed in some other manner.
• Confirm that you have used a tool such as [Grammarly] to verify that the text is correct.
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  • The preview has your tutorial listed.
  • The preview looks like what you want.

[arnavk23]

@tmigot please review this pr.

[tmigot]

Please make sure that the code you suggest work before your PR and ask in the issue if something is not clear. Thanks!!