[JVM IR] Copy metadata in IrFieldBuilder.

This fixes an issue with lateinit properties where the metadata from
the original field was not copied to the nullable field in
LateinitLowering. Also consolidated related tests.

compiler/testData/codegen/box/reflection/mapping/topLevelProperty.kt

@@ -4,7 +4,7 @@
 // WITH_REFLECT
 
 import kotlin.reflect.jvm.*
-import kotlin.test.assertEquals
+import kotlin.test.*
 
 var topLevel = "123"
 
@@ -13,19 +13,21 @@ val fileFacadeClass = object {}::class.java.enclosingClass
 fun box(): String {
     val p = ::topLevel
 
-    assert(p.javaField != null) { "Fail p field" }
-    val field = p.javaField!!
-    assertEquals(fileFacadeClass, field.getDeclaringClass())
+    assertNotNull(p.javaField, "Fail p field")
+    assertEquals(p.javaField!!.getDeclaringClass(), fileFacadeClass)
 
     val getter = p.javaGetter!!
     val setter = p.javaSetter!!
 
-    assertEquals(getter, fileFacadeClass.getMethod("getTopLevel"))
-    assertEquals(setter, fileFacadeClass.getMethod("setTopLevel", String::class.java))
+    assertEquals(fileFacadeClass.getMethod("getTopLevel"), getter)
+    assertEquals(fileFacadeClass.getMethod("setTopLevel", String::class.java), setter)
 
-    assert(getter.invoke(null) == "123") { "Fail k getter" }
+    assertNull(p.getter.javaConstructor)
+    assertNull(p.setter.javaConstructor)
+
+    assertEquals("123", getter.invoke(null), "Fail k getter")
     setter.invoke(null, "456")
-    assert(getter.invoke(null) == "456") { "Fail k setter" }
+    assertEquals("456", getter.invoke(null), "Fail k setter")
 
     return "OK"
 }