[FIR] Introduce ConeFunctionalTypeKind as a replacement of FunctionClassKind

This is needed to provide an ability to extend different kinds of
  functional types

Also, cleanup and rename utilities related to functional types to avoid
  possible confusions

compiler/visualizer/render-fir/src/org/jetbrains/kotlin/compiler/visualizer/FirVisualizer.kt

@@ -337,7 +337,10 @@ class FirVisualizer(private val firFile: FirFile) : BaseRenderer() {
                 return
             }
             val projectionBuilder = StringBuilder()
-            ConeTypeRendererForDebugging(projectionBuilder).renderAsPossibleFunctionType(this) {
+            ConeTypeRendererForDebugging(projectionBuilder).renderAsPossibleFunctionType(
+                this,
+                { it.functionalTypeKind(session) }
+            ) {
                 localTypeProjectionRenderer(projectionBuilder)
             }
             builder.append(projectionBuilder.toString().removeCurrentFilePackage())