LL API: add basic tests for kt -> fir mapping

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -62,6 +62,7 @@ class FirRenderer(builder: StringBuilder, private val mode: RenderMode = RenderM
         val renderPropertyAccessors: Boolean = true,
         val renderDeclarationAttributes: Boolean = false,
         val renderDeclarationOrigin: Boolean = false,
+        val renderPackageDirective: Boolean = false,
     ) {
         companion object {
             val Normal = RenderMode(
@@ -1368,4 +1369,10 @@ class FirRenderer(builder: StringBuilder, private val mode: RenderMode = RenderM
     override fun visitContractDescription(contractDescription: FirContractDescription) {
         require(contractDescription is FirEmptyContractDescription)
     }
+
+    override fun visitPackageDirective(packageDirective: FirPackageDirective) {
+        if (mode.renderPackageDirective) {
+            println("package ${packageDirective.packageFqName.asString()}")
+        }
+    }
 }