Adding recipe for Listenable Maps for Audio Classifiers

[fpaissan]

What does this PR do?

• Implements the work of the ICML'24 paper L-MAC (https://arxiv.org/abs/2403.13086).
• Refactors exiting L2I and PIQ recipes to unify the interpretability approaches under a single structure. This simplifies code shared among the interpretability pipelines. Also, it minimizes the room for error in the comparison of the techniques.

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