Add doobie-postgres-tethys integration

How do you feel about adding a new module with Put and Get instances for json and jsonb for tethys similar to doobie-postgres-circe?

smth like that

trait JsonBTethysInstances {

  implicit private val showPGobject: Show[PGobject] = Show.show(_.getValue.take(250))

  def jsonbPut[T: JsonWriter]: Put[T] =
    Put.Advanced.other[PGobject](
      NonEmptyList.of("jsonb")
    ).tcontramap { a =>
      val o = new PGobject
      o.setType("jsonb")
      o.setValue(a.asJson)
      o
    }

  def jsonbGet[T: JsonReader]: Get[T] =
    Get.Advanced.other[PGobject](
      NonEmptyList.of("jsonb")
    ).temap(_.getValue.jsonAs[T].leftMap(_.getMessage))
}

and the similar for "json"

Start by examining the existing doobie-postgres-circe module and the Tethys JsonWriter and JsonReader APIs. Add the proposed doobie-postgres-tethys module with Put and Get instances for both json and jsonb, then verify that the integration handles PostgreSQL values as shown in the issue.