feat: Document presence indicator (#1114)

* Update websockets to allow joining document-based rooms

* dynamic websocket joining

* emit user.join/leave events when entering and exiting document rooms

* presence storage

* feat: frontend presence store

* lint

* UI updates

* First pass editing state

* refactoring

* Timeout per user/doc
lint

* Document data loading refactor to keep Socket mounted

* restore: Mark as viewed functionality
Add display of 'you' to collaborators

* fix: Socket/document remount when document slug changes due to title change

* Revert unneccessary package update

* Move editing ping interval to a shared constant

* fix: Flash of sidebar when loading page directly on editing mode

* separate document and revision loading

* add comments for socket events

* fix: Socket events getting bound multiple times on reconnect

* fix: Clear client side presence state on disconnect

* fix: Don't ignore server side error
Improved documentation

* More comments / why comments

* rename Socket -> SocketPresence

* fix: Handle redis is down
remove unneccessary join

* fix: PR feedback

app/scenes/Document/components/Header.js

@@ -143,13 +143,16 @@ class Header extends React.Component<Props> {
           </Title>
         )}
         <Wrapper align="center" justify="flex-end">
-          {!isDraft && !isEditing && <Collaborators document={document} />}
           {isSaving &&
             !isPublishing && (
               <Action>
                 <Status>Saving…</Status>
               </Action>
             )}
+          <Collaborators
+            document={document}
+            currentUserId={auth.user ? auth.user.id : undefined}
+          />
           {!isDraft &&
             !isEditing &&
             canShareDocuments && (