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/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/components/JavaPropertyInitializerEvaluator.kt

@@ -23,11 +23,7 @@ import org.jetbrains.kotlin.resolve.constants.ConstantValue
 interface JavaPropertyInitializerEvaluator {
     fun getInitializerConstant(field: JavaField, descriptor: PropertyDescriptor): ConstantValue<*>?
 
-    fun isNotNullCompileTimeConstant(field: JavaField): Boolean
-
     object DoNothing : JavaPropertyInitializerEvaluator {
         override fun getInitializerConstant(field: JavaField, descriptor: PropertyDescriptor) = null
-
-        override fun isNotNullCompileTimeConstant(field: JavaField) = false
     }
 }

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/lazy/descriptors/LazyJavaScope.kt

@@ -285,7 +285,7 @@ abstract class LazyJavaScope(protected val c: LazyJavaResolverContext) : MemberS
     private fun getPropertyType(field: JavaField, annotations: Annotations): KotlinType {
         // Fields do not have their own generic parameters.
         // Simple static constants should not have flexible types.
-        val allowFlexible = !(field.isFinalStatic && c.components.javaPropertyInitializerEvaluator.isNotNullCompileTimeConstant(field))
+        val allowFlexible = !(field.isFinalStatic && field.hasConstantNotNullInitializer)
         val propertyType = c.typeResolver.transformJavaType(
                 field.type,
                 LazyJavaTypeAttributes(TypeUsage.MEMBER_SIGNATURE_INVARIANT, annotations, allowFlexible)

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/structure/javaElements.kt

@@ -97,6 +97,8 @@ interface JavaMethod : JavaMember, JavaTypeParameterListOwner {
 interface JavaField : JavaMember {
     val isEnumEntry: Boolean
     val type: JavaType
+    val initializerValue: Any?
+    val hasConstantNotNullInitializer: Boolean
 }
 
 interface JavaConstructor : JavaMember, JavaTypeParameterListOwner {