FIR: introduce delegate field initializers

Before this commit we initialized delegate fields in primary constructor,
that could provoke NPE in case delegate is used in initializer of
some property backing field.
Now we initialize delegate fields directly instead.

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/declarations/FirJavaField.kt

@@ -148,7 +148,6 @@ internal class FirJavaFieldBuilder : FirFieldBuilder() {
     var modality: Modality? = null
     lateinit var visibility: Visibility
     var isStatic: Boolean by Delegates.notNull()
-    var initializer: FirExpression? = null
     lateinit var annotationBuilder: () -> List<FirAnnotationCall>
 
     override var resolvePhase: FirResolvePhase = FirResolvePhase.ANALYZED_DEPENDENCIES