fix(cache): support multi-index and multiple queries per index

[aymeric-giraudet]

Summary

FX-2938

Fixes part of #6258 and #6259

Result

• A single index may cause up to 3 requests at once, if it has facets applied or hierarchical facets, so request params should be an array.
• Shape of a cached request is { method: 'search', args: [Array<QueryParams>] }, not { method: 'search', args: Array<Array<QueryParams>> } as it takes a single argument which is an array of params.

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example-instantsearch-getting-started	Configuration
example-react-instantsearch-getting-started	Configuration
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example-react-instantsearch-next-routing-example	Configuration
example-vue-instantsearch-getting-started	Configuration

[Haroenv]

Which parts of https://github.com/algolia/instantsearch/issues/6258 and https://github.com/algolia/instantsearch/discussions/6259 aren't solved in this PR?

[aymeric-giraudet]

@Haroenv this one :

Now click on Women, there is a data request(which handles SSR via the loader using getServerState) and there is also an unnecessary client side query.

We would need to react to initialResults changes and totally opt-out of client-side requesting, or just have Remix users not call the loader if possible as it may add unnecessary overhead

And the one at the end of #6259 is unrelated too. I'll ask them to split once this is done

[Haroenv]

In that case I think the issue identified in https://github.com/algolia/instantsearch/issues/6258 can be marked as done, and the part where the remix integration docs is wrong can be a separate ticket :)