Custom clients / proxy settings are missing.

[papaIOprog]

Description
I work behind proxy server and I can't configure plugin to work with it. In meilisearch-js library you can specify custom client for MeiliSearch. This gatsby plugin doesn't have httpClient parameter for custom clients.

Expected behavior
Be able to specify custom client/proxy.

Current behavior
No such parameter.

[brunoocasali]

Yes indeed @papaIOprog it would be very nice to have!

Unfortunately, we have a short time to work on new features for this repository, so if you or anyone else wants to make a contribution we would be happy to review!