Remove internal transformResponse option

[kettanaito]

Scope

Improves an existing behavior

Compatibility

• This is a breaking change

Feature description

This shouldn't be needed anymore:

msw/src/core/utils/handleRequest.ts

Lines 25 to 29 in 6702d77

	/**
	* Transforms a `MockedResponse` instance returned from a handler
	* to a response instance supported by the lower tooling (i.e. interceptors).
	*/
	transformResponse?(response: Response): Response

This option used to exist to provide response format compatibility between the consumer and the interceptors. Now, it's always the Fetch API Response. We need to remove this option and its usage altogether.