FIR: Report CAPTURED_VAL_INITIALIZATION if initialization is done

outside of constructor.

In other words, when EXACTLY_ONCE lambda initializes non-static final
field of a class, the lambda has to be inlined, otherwise, backend
generated separate function of separate class for the lambda,
which lead to exception at runtime.

 #KT-64854 Fixed
 #KT-59906 Fixed

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

@@ -86,7 +86,7 @@ class DefiniteInitializationInInitSection {
     <!MUST_BE_INITIALIZED_OR_BE_ABSTRACT!>val y: Int<!>
 
     init {
-        myRun { x = 42 }
+        myRun { <!CAPTURED_VAL_INITIALIZATION!>x<!> = 42 }
         unknownRun { <!CAPTURED_MEMBER_VAL_INITIALIZATION!>y<!> = 239 }
     }
 }