[K/N] Add objcClassesIncludingCategories cinterop property

It allows to list Objective-C classes that should include
corresponding categories from the same file.
The current implementation is super-simple and slow, but
it is OK since it is not intended to be a general-purpose
solution for now.

kotlin-native/shared/src/main/kotlin/org/jetbrains/kotlin/konan/util/DefFile.kt

@@ -132,6 +132,9 @@ class DefFile(val file:File?, val config:DefFileConfig, val manifestAddendProper
             properties.getProperty("plugin")
         }
 
+        val objcClassesIncludingCategories by lazy {
+            properties.getSpaceSeparated("objcClassesIncludingCategories")
+        }
     }
 }