Forbid val field initialization inside EXACLTY_ONCE lambda

unless the lambda is inline. This way, final field will remain final.

compiler/testData/codegen/box/contracts/field.kt

@@ -1,26 +0,0 @@
-// !USE_EXPERIMENTAL: kotlin.contracts.ExperimentalContracts
-// IGNORE_BACKEND: NATIVE
-// WITH_RUNTIME
-// IGNORE_LIGHT_ANALYSIS
-
-import kotlin.contracts.*
-
-fun runOnce(action: () -> Unit) {
-    contract {
-        callsInPlace(action, InvocationKind.EXACTLY_ONCE)
-    }
-    action()
-}
-
-class Foo {
-    val res: String
-    init {
-        runOnce {
-            res = "OK"
-        }
-    }
-}
-
-fun box(): String {
-    return Foo().res
-}