[Depends on #3698] Rework SolutionLoader

[michaelbynum]

Summary/Motivation:

This PR updates the solution loader in pyomo/contrib/solver based on recent design discussions.

Changes proposed in this PR:

• add get_number_of_solutions method
• add get_solution_ids method
• add load_solution_method
• add load_import_suffixes method
• add solution_id as an argument to methods

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