Minor, extract test for synthetic methods for properties

compiler/testData/codegen/properties/syntheticMethod/inClass.kt

@@ -0,0 +1,8 @@
+import java.lang.annotation.*
+
+Retention(RetentionPolicy.RUNTIME) annotation class SomeAnnotation(val value: String)
+
+class A {
+    [SomeAnnotation("OK")] val property: Int
+        get() = 42
+}

compiler/testData/codegen/properties/syntheticMethod/topLevel.kt

@@ -0,0 +1,6 @@
+import java.lang.annotation.*
+
+Retention(RetentionPolicy.RUNTIME) annotation class SomeAnnotation(val value: String)
+
+[SomeAnnotation("OK")] val property: Int
+    get() = 42