Refactored diagramToString method as factDiagram method in Fact, and removed the private[scalatest] val of left and right in Binary_&& and Binary_||.
Refactored diagramToString method as factDiagram method in Fact, and removed the private[scalatest] val of left and right in Binary_&& and Binary_||.

scalatest/scalatest,dotty-staging/scalatest,dotty-staging/scalatest,cheeseng/scalatest,cheeseng/scalatest,scalatest/scalatest,dotty-staging/scalatest,cheeseng/scalatest,scalatest/scalatest