[Swift Export] KT-65008: support simple top-level properties

Merge-request: KT-MR-14131
Merged-by: Gleb Lukianets <Gleb.Lukianets@jetbrains.com>

native/swift/sir/tree-generator/src/org/jetbrains/kotlin/sir/tree/generator/BuilderConfigurator.kt

@@ -22,5 +22,9 @@ class BuilderConfigurator(elements: List<Element>) : AbstractSwiftIrTreeBuilderC
         configureFieldInAllLeafBuilders("visibility") {
             default(it, "SirVisibility.PUBLIC")
         }
+
+        builder(setter) {
+            default("parameterName", "\"newValue\"")
+        }
     }
 }

native/swift/sir/tree-generator/src/org/jetbrains/kotlin/sir/tree/generator/SwiftIrTree.kt

@@ -78,9 +78,15 @@ object SwiftIrTree : AbstractSwiftIrTreeBuilder() {
         parent(declaration)
     }
 
+    // Denotes "actual" callable node. (I.e. SirCallable & !SIRForeignDeclaration)
+    // TODO: remove along with foreign declaration (KT-65335); replace usages with just SIRCallable
+    val nativeCallable by sealedElement {
+        parent(callable)
+    }
+
     val function by element {
         customParentInVisitor = callable
-        parent(callable)
+        parent(nativeCallable)
 
         +field("isStatic", boolean) // todo: KT-65046 Method|function distinction in SIR
         +field("name", string)
@@ -98,4 +104,42 @@ object SwiftIrTree : AbstractSwiftIrTreeBuilder() {
 
         visitorParameterName = "function"
     }
+
+    val accessor by sealedElement {
+        customParentInVisitor = callable
+        parent(nativeCallable)
+
+        +field("body", functionBodyType, nullable = true, mutable = true)
+    }
+
+    val getter by element {
+        parent(accessor)
+    }
+
+    val setter by element {
+        parent(accessor)
+
+        +field("parameterName", string, initializer = {  })
+    }
+
+    val variable by element {
+        customParentInVisitor = declaration
+        parent(declaration)
+        parent(declarationParent)
+
+        +field("name", string)
+        +field("type", typeType)
+
+        +field("getter", getter)
+        +field("setter", setter, nullable = true)
+
+        +field("isStatic", boolean) // todo: KT-65046 Method|function distinction in SIR
+    }
+
+    val foreignVariable by element {
+        customParentInVisitor = declaration
+        parent(foreignDeclaration)
+
+        visitorParameterName = "variable"
+    }
 }