Remove scalacheck fork by implementing buildableOfCollCond

[mdedetrich]

About this change - What it does

Replaces fork of scalacheck with official upstream one and as a result implements listOfFillCond natively.

Why this way

Initially a fork of scalacheck was made in order to implement the ability to create a continuously growing generator. The fork was done because at the time I thought it was not possible to implement this without modifying the core of scalacheck. It turns out that I was incorrect in this, scalacheck has a Gen.infiniteLazyList which can be used to implement this functionality (see typelevel/scalacheck#849 (comment))

[reta]

The only option I see (without introducing the mutable state) is something like this (pseudo code, probably needs some scalafication):

while (true) {
  val result = bldr.result();
  if (cond(result)) {
    return result;
  }
  bldr ++= it.next()
}

[mdedetrich]

Thanks for recommendation, I wanted to avoid this because it involved having to circumvent Scala's lint warnings but I managed to find a way. Just pushed it now to see if tests pass.

[mdedetrich]

So I tried a solution, i.e.

@SuppressWarnings(
  Array(
    "scalafix:DisableSyntax.while",
    "scalafix:DisableSyntax.return"
  )
)
@scala.annotation.nowarn("msg=return statement uses an exception")
private def buildableOfCollCond[C <: Iterable[T], T](cond: C => Boolean, g: Gen[C])(implicit
    evb: Buildable[T, C]
): Gen[C] =
  Gen.infiniteLazyList(g).map { ll =>
    val it   = ll.iterator
    val bldr = evb.builder
    while (true) {
      val result = bldr.result()
      if (cond(result)) {
        return result
      }
      bldr ++= it.next()
    }
    return bldr.result()
  }

And it didn't work/terminate. Don't have time to look at this now so I will make an issue to look at it later as an improvement.