Mark deprecated FunctionURLResponse init as @_disfavoredOverload (#93)

In a previous PR (#91), a new init with a different parameters order was
added, marking the previous one was deprecated. The problem is that the
compiler doesn't know which one to choose when omitting the final
parameters.

This PR fixes it by marking the deprecated init with
`@_disfavoredOverload`.

Author: natanrolnik

Sources/AWSLambdaEvents/FunctionURL.swift

@@ -95,6 +95,7 @@ public struct FunctionURLResponse: Codable, Sendable {
     public var isBase64Encoded: Bool?
 
     @available(*, deprecated, message: "Use init(statusCode:headers:body:isBase64Encoded:cookies:) instead")
+    @_disfavoredOverload
     public init(
         statusCode: HTTPResponse.Status,
         headers: HTTPHeaders? = nil,