New generator for Scala3 + sttp4 + jsoniter-scala #1044

Job	Run time
Build sbt/Scala client, servers (samples/client/petstore/scalaz)	56s
Build sbt/Scala client, servers (samples/client/petstore/java/okhttp-gson)	53s
Build sbt/Scala client, servers (samples/server/petstore/scala-http4s-server)	1m 1s
Build sbt/Scala client, servers (samples/server/petstore/scalatra)	59s
Build sbt/Scala client, servers (samples/client/petstore/scala-pekko)	51s
Build sbt/Scala client, servers (samples/client/petstore/scala-sttp4-jsoniter)	1m 3s
Build sbt/Scala client, servers (samples/server/petstore/scala-play-server)	3m 42s
Build sbt/Scala client, servers (samples/client/petstore/scala-http4s)	56s
Build sbt/Scala client, servers (samples/server/petstore/scala-pekko-http-server)	52s
Build sbt/Scala client, servers (samples/server/petstore/scala-lagom-server)	5m 41s
Build sbt/Scala client, servers (samples/server/petstore/scala-akka-http-server)	48s
Build sbt/Scala client, servers (samples/server/petstore/scala-cask)	1m 27s
	19m 9s

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