fs2

This is a follow-up from http4s/http4s#6325.
Ross made a proposal that we can don't create Ref in a case when the request/response body isn't streaming.
One should keep in mind, that a single Ref instance is reusing.

full example from https://github.com/tpolecat/skunk/blob/v0.0.24/modules/docs/src/main/paradox/tutorial/Command.md
gives following compile errors

skunk-world/src/main/scala/CommandExample.scala:42:34
not found: type *
  def fromSession[F[_] : Bracket[*[_], Throwable]](s: Session[F]): PetService[F] =

skunk-world/src/main/scala/CommandExample.scala:42:24
cats.effect.Bracket[<error>,Thro

Similarly to #234, it would be useful to provide functions for creating test KafkaProducers.

A good first function would be one which yields somewhat sensible default RecordMetadata.

object KafkaProducer {
  def unit[F[_], K, V](implicit F: Sync[F]): F[KafkaProducer[F, K, V]] = ???
}

Likely, this would require some internal state, hence F[KafkaProducer[F, K, V]].

See

• https://47deg.github.io/sbt-microsites/
• in conjunction with http://tpolecat.github.io/tut/

Consider replacing ScalaTest with weaver-test.