feat: add support of objects in query params

[aleksej-axiology]

[!NOTE] Enhances query serialization to handle objects and arrays using bracketed keys (key[index]/key[subkey]) in fetch-http-client.ejs.

• HTTP Client Template (templates/base/http-clients/fetch-http-client.ejs):
  • Query serialization:
    • addArrayQueryParam: now serializes arrays as key[index]=value and objects via Object.entries, emitting key[subkey]=value.
    • toQueryString: treats both objects and arrays as complex params, delegating to addArrayQueryParam; primitives use addQueryParam.

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