Assert using message builder

[tokazio]

Allow using a StringBuilder as a message builder to dynamically build the assertion result message.

Konsist
        .scopeFromPackage("$packageName..")
        .classes()
        .assertTrue(testName="bla bla") { classDeclaration, messageBuilder ->
            val ctorProperties = classDeclaration.primaryConstructor!!.parameters.mapTo(mutableSetOf()) { param -> param.name }
            val actualSettableClassProperties = classDeclaration.properties()
            val missingProperties = actualSettableClassProperties - copyProperties
            if (missingProperties.isNotEmpty()) {
              messageBuilder?.appendLine(
                "${classDeclaration.name} has ${missingProperties.size} copiable properties outside of its ctor:\n ${
                missingProperties.joinToString("\n") { "\t* $it" }
              }"
              )
              false
            } else true
          }
        }

will produce a message like:

Assert 'bla bla' was violated (1 time).
MyClass has 2 copiable properties outside of its ctor:
 	* plip
	* plop

I've removed the 'additionalMessage' for these calls and kept retro compatibility to existing assertXXX calls