[FIR/IR generator] Add kDoc property to AbstractElement & AbstractField

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/model/Element.kt

@@ -30,6 +30,8 @@ class Element(override val name: String, kind: Kind) : AbstractElement<Element,
     override val nullable: Boolean
         get() = false
 
+    override var kDoc: String? = null
+
     override val fields = mutableSetOf<Field>()
     override val type: String = "Fir$name"
     override val packageName: String = BASE_PACKAGE + kind.packageName.let { if (it.isBlank()) it else "." + it }

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/model/Field.kt

@@ -63,6 +63,7 @@ sealed class Field : AbstractField() {
         }
         copy.fromParent = fromParent
         copy.parentHasSeparateTransform = parentHasSeparateTransform
+        copy.kDoc = kDoc
     }
 
     protected abstract fun internalCopy(): Field

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/printer/element.kt

@@ -39,6 +39,7 @@ fun SmartPrinter.printElement(element: Element) {
             }
         }
 
+        printKDoc(kDoc)
         print("${kind!!.title} $type")
         print(typeParameters())
         val parentRefs = element.parentRefs

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/printer/field.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.tree.generator.printer
 
 import org.jetbrains.kotlin.fir.tree.generator.model.Field
+import org.jetbrains.kotlin.generators.tree.printer.printKDoc
 import org.jetbrains.kotlin.utils.SmartPrinter
 import org.jetbrains.kotlin.utils.withIndent
 
@@ -17,6 +18,10 @@ fun SmartPrinter.printField(
     inConstructor: Boolean = false,
     modifiers: SmartPrinter.() -> Unit = {},
 ) {
+    if (!override && field.kDoc != null) {
+        println()
+        printKDoc(field.kDoc)
+    }
     if (!field.isVal && field.isVolatile) {
         println("@Volatile")
     }