ActiveRecord-like sanitization on filter

[ellnix]

While Meilisearch is not meant to be a database in the traditional sense, I think it's possible for sensitive data to end up in indexes.

I think we should support sanitized parameters in methods like filter, similar to ActiveRecord, by having ? and ?<number> as placeholders and successive arguments that fill in the placeholders.

This issue is just as stub for high level discussion, since I would like to research how ActiveRecord does it before talking about implementation details.

[ellnix]

@brunoocasali What do you think about this?