Change the way we infer the types of steps arguments

[gaeljw]

This PR significantly changes the way the types of steps arguments are "inferred" by Cucumber Scala.

The main difficulity being generic types like List[Map[String, String]] (used for instance for datatables).

Current situation (Scala 2)

We rely on the scala reflection Manifest mechanism which overcome the JVM type erasure.

In recent Scala 2 versions, Manifests are deprecated but still available. The replacement being TypeTags which could be used in a very similary way.

Future (Scala 3)

With Scala 3, both Manifest and TypeTags are removed with no direct replacement.

I tried to mimic the behaviour by using macros in a previous PR (#186) thanks to a home made library (typetrees). This was working but:

• it doesn't feel right to have to use macros for our need
• it hardens maintability as the Scala 2 and Scala 3 code are really different
• it brings dependence on an "unproven" 3rd party library.

Proposition

This PR changes the way we infer types by using a well-known typeclass mechanism.

Argument of a step must have a type T that conforms to the typeclass Stepable[T]. This typeclass being defined as:

trait Stepable[T] {
  def asJavaType: JavaType
}

Implicit values of Stepable are provided for all non generic types and generic types with less than 10 parameters (any combination of these being possible).

This might sound like we are reducing the possibilities of types allowed in step arguments and it is the case for generic types with more than 9 parameters but:

1. I don't see many use case for such types
2. We can always implement other implicit values in the future

TODO

• Add unit tests on Stepable implicits
• I will test this PR on our big projects at work to check for undesired side effect.

Additional note: we still need a slightly different code in StepDsl between Scala 2 and Scala 3 but not related to the types of step arguments, only to some construction not allowed anymore in Scala 3 for handling both fn: => Unit and fn: () => Unit.