FAI-882: Add kwargs to explainers

[RobGeada]

The benchmarks repo required the explainers to have kwargs; the SHAP and LIME now use kwargs for:

• SHAP: everything but background, link_type
• LIME: everything but samples

Docs are updated accordingly

[ruivieira]

@RobGeada LGTM, thanks.

As note for the future, we might want to type the **kwargs as a TypedDict with corresponding typing. This will allow for code completion when PEP692 is accepted (potentially Python 3.12).

[tteofili]

LGTM