Macro API with Context Parameters

[bloderxd]

What

This PR brings a design proposal using Kotlin Context Parameters feature to Macros API. The idea is to use the power of context parameter to build elegant and simple macro code, the proposals are:

Context Parameter in Macro functions

Now developers can write macros using the benefits of context parameters:

@Macro(target = Product::class)
context(_: MacroContext)
fun product(firClass: FirClass): MacroCompilation {
  return firClass.transform {
    //language=kotlin
    """
      fun product(): List<Pair<String, *>> {               
        return listOf(${firClass.properties { """"${+it.name}" to this.${+it.name}""" }})
      }
    """.function().create()
  }
}

Some internal functions were also improved, for example properties that is a new version of propertiesOf, letting all macro construction more idiomatic and simple.

Changes in TransformClassCompilation

The proposal in this compilation is to improve members construction in this compilation, so instead of:

firClass.transform {
  property {
    """
      val b = 2
    """
  }
  function {
    """
      fun a() {}
    """
  }
  function {
    """
      fun b() {}
    """
  }
}

This PR proposes:

firClass.transform {
  """
    val b = 2
  """.property().create()
  """
    fun a() {}
  """.function().create()
  """
    fun b() {}
  """.function().create()
}

I'm not totally against curly braces style but I feel it's more clear and simple if we try to let this class transformation scope linear. The idea to divide create function from property and function functions for example, is to separate its concerns letting create function type safe but let me know if you prefer another approach like "val b = 2".createProperty() and "fun a() {}".createFunction

[raulraja]

Looks great!