LPS-31950 Add social activities for wiki attachments
LPS-31950 These are sorted by model-name, then by language-key, keep the same order.
LPS-31950 Use the same grammar rules that are already applied to other language keys.
LPS-31950 Reverted changes to Language.properties since they are not following the same grammar rules applied to existing activity keys. "A wiki page" vs "The wiki page" or just "Wiki page". What's the difference between activity-wiki-add-attachment-page and activity-wiki-add-the-attachment ?