feat(kitsu): Configurable modern query serializer

[pedep]

Resolves discussion from #781

This PR aims to introduce the following:

1. Parse key names like id_in[] and id_in][ and ensure they appear intuitively in the query (filter[id_in][])
   Previous behaviour would generate keys like filter[id_in[]], requiring unintuitive keys id_in][ in order to achieve the expected behaviour.
2. Make the query method configurable, by allowing an option to be passed to the Kitsu class constructor
   2.1 Allow the user to switch between traditional (current behaviour) and modern mode. Modern mode allows to automatic generation of array style keys when passing an array to params, instead of having to explicitly declare them:
   traditional api.get('anime', {filter: {id_in[]: [1,2]}}) -> filter[id_in][]=1&filter[id_in][]=2
   modern api.get('anime', {filter: {id_in: [1,2]}}) -> filter[id_in][]=1&filter[id_in][]=2
   2.2 Allow arbitrary serialization functions to be passed, for customized handling ((obj: any) => string)
   const api = new Kitsu({ query: (obj) => /* handle serialization */ })

[codeclimate]

Code Climate has analyzed commit 4974425 and detected 0 issues on this pull request.

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[wopian]

Released as 10.1.0