FIR checker: report uninitialized member/extension properties

compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valDefiniteInitialization.fir.kt

@@ -83,7 +83,7 @@ fun unknownRun(block: () -> Unit) = block()
 
 class DefiniteInitializationInInitSection {
     val x: Int
-    val y: Int
+    <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>val y: Int<!>
 
     init {
         myRun { x = 42 }

compiler/testData/diagnostics/testsWithStdLib/contracts/controlflow/initialization/exactlyOnce/valIndefiniteInitialization.fir.kt

@@ -60,7 +60,7 @@ fun nestedIndefiniteAssignment() {
 }
 
 class InitializationForbiddenInNonInitSection {
-    val x: Int
+    <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>val x: Int<!>
 
     fun setup() {
         myRun { x = 42 }