[FIR] Add FirCodeFragment

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

@@ -64,6 +64,7 @@ object FirTreeBuilder : AbstractFirTreeBuilder() {
     val constructor by element(Declaration, function, typeParameterRefsOwner, contractDescriptionOwner)
     val file by element(Declaration, declaration)
     val script by element(Declaration, declaration)
+    val codeFragment by element(Declaration, declaration)
     val packageDirective by element(Other)
 
     val anonymousFunction by element(Declaration, function, typeParametersOwner, contractDescriptionOwner)

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

@@ -495,6 +495,11 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
             +fieldList(contextReceiver, useMutableOrEmpty = true)
         }
 
+        codeFragment.configure {
+            +symbol("FirCodeFragmentSymbol")
+            +field(block).withTransform()
+        }
+
         packageDirective.configure {
             +field("packageFqName", fqNameType)
         }