PLT-3960 Don't show (message deleted) placeholder to the user that deleted the message (#4839)

* on post delete remove the whole post for the owner of the post while other user will still see post deleted message

* now the deleter wont see the post while the other users will see deleted message

* removed fromSocket check and now calling PostStore.removePost instead of PostStore.deletePost from view

* fixed the bug which was causing to show message deleted until next action

* added remove post from store to global action

* moved removePostFromStore from global actions to post actions

webapp/actions/post_actions.jsx

@@ -362,3 +362,8 @@ export function createPost(post, doLoadPost, success, error) {
         }
     );
 }
+
+export function removePostFromStore(post) {
+    PostStore.removePost(post);
+    PostStore.emitChange();
+}