New generator for Scala3 + sttp4 + jsoniter-scala #1047

Job	Run time
Build sbt/Scala client, servers (samples/client/petstore/scalaz)	1m 3s
Build sbt/Scala client, servers (samples/client/petstore/scala-http4s)	1m 1s
Build sbt/Scala client, servers (samples/client/petstore/java/okhttp-gson)	53s
Build sbt/Scala client, servers (samples/client/petstore/scala-pekko)	1m 2s
Build sbt/Scala client, servers (samples/server/petstore/scala-akka-http-server)	48s
Build sbt/Scala client, servers (samples/server/petstore/scala-lagom-server)	5m 30s
Build sbt/Scala client, servers (samples/client/petstore/scala-sttp4-jsoniter)	54s
Build sbt/Scala client, servers (samples/server/petstore/scala-play-server)	4m 30s
Build sbt/Scala client, servers (samples/server/petstore/scalatra)	58s
Build sbt/Scala client, servers (samples/server/petstore/scala-pekko-http-server)	54s
Build sbt/Scala client, servers (samples/server/petstore/scala-http4s-server)	54s
Build sbt/Scala client, servers (samples/server/petstore/scala-cask)	1m 25s
	19m 52s

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