PSI2IR: generate field writes for all val property assignments

Assuming the frontend is correct, and it hopefully is, all of them are
initializations even if not done in the owner class directly.

compiler/testData/codegen/boxInline/contracts/propertyInitialization.kt

@@ -1,6 +1,5 @@
 // !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
-// IGNORE_BACKEND: JVM_IR, JS_IR, NATIVE
-// IGNORE_BACKEND_MULTI_MODULE: JVM_IR
+// IGNORE_BACKEND: NATIVE
 
 // FILE: 1.kt