Introduce initializer-related properties into JavaField

It's much more convenient to use and implement these
properties instead of manual "pattern matching" in the
JavaPropertyInitializerEvaluatorImpl

core/descriptors.runtime/src/org/jetbrains/kotlin/load/java/structure/reflect/ReflectJavaField.kt

@@ -25,4 +25,7 @@ class ReflectJavaField(override val member: Field) : ReflectJavaMember(), JavaFi
 
     override val type: ReflectJavaType
         get() = ReflectJavaType.create(member.genericType)
+
+    override val initializerValue get() = null
+    override val hasConstantNotNullInitializer get() = false
 }