feat(createInstantSearch): enable _useRequestCache

[samouss]

Summary

This PR enable the option _useRequestCache on the default client. It doesn't impact clients that don't support this option. We don't apply the option on searchClient because when you provide your own implementation you want to control which option is applied to the client.

[algobot]

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[vvo]

Curious: does this solve any issue like duplicate requests right now? 🙏

[Haroenv]

this isn't a breaking change since it isn't called on a search client if it's passed and accessing cache isn't really possible here. If what you showed earlier that this fixes the duplicate requests still works, then you can say this fixes #1037

[Haroenv]

probably some other issues too

[samouss]

I didn't manage to have a working demo because CodeSandbox doesn't download the correct version of the client. But you can download the sandbox it works locally (see below). The example simulate an application with code splitting where the SearchBox is mounted after the rest of the page. By default it triggers two requests, but with the option it triggers only one.

https://codesandbox.io/s/zzqnllyqq3

Before

After