[typescript-fetch] support explode query parameters

Created by: bobvanderlinden

Related to https://github.com/OpenAPITools/openapi-generator/issues/3781

Currently multiple query parameters that are serialized as CSV. param: [1,2,3] becomes param=1,2,3.

The OpenAPI specification https://swagger.io/docs/specification/serialization/#query says the default serialization for query parameters with multiple values is style: form with explode: true. That means that means that serialization for param: [1,2,3] should be param=1&param=2&param=3.

This PR attempts to add such support for explode for typescript-fetch.

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