Add id to getEntry return as fallback

This modification allows us to later filterEntry if the entry is not found. 

The usecase for it is:
1. while using it with soft-delete plugin, the soft-delete first update and then delete it.
2. the way it is right now, filterEntry receives an empty object, so we can't trace what is this entry.
3. If we add the `id`, I believe there is no implication, and we can use it to build our logic at filterEntry, knowing at least the id.

This is our usecase, but I believe having the id can be useful in other scenarios that uses filterEntry, because at least you receive a relevant information at the filterEntry function.

Author: matepaiva

server/services/content-types/content-types.js

@@ -148,7 +148,7 @@ module.exports = ({ strapi }) => ({
       strapi.log.error(`Could not find entry with id ${id} in ${contentType}`)
     }
 
-    return entry || {}
+    return entry || { id }
   },
 
   /**