Allow Multiple Invites to Party (#8683)

* (server) Add parties array to store invites

* (server) Lint files

* Update joinGroup, rejectGroupInvite, _inviteByUUID, and remove clearPartyInvitation.js

* Update user schema: detailed 'invitations.parties' attributes

* Code improvement and do not let invite twice

* Check if the user is already invited earlier in the code

* Added message to invitation page, and show all invitations

* Added join party confirmation alert

* Small fixes

* Created test: allow inviting a user to 2 different parties

* Updated tests

* Update invitations.parties on more places

* Small adjustments

* Updates on invitations.party references

* Show all invitations when user is already in a party

* Fixed notifications counter

* Update both 'party' and 'parties' at _handleGroupInvitation

* Updated a test

* Fixed small mistake at _handleGroupInvitation

* More test update

* Update invitation.party when removing single invite and small adjust at view

website/server/controllers/api-v3/auth.js

@@ -46,6 +46,7 @@ async function _handleGroupInvitation (user, invite) {
 
     if (group.type === 'party') {
       user.invitations.party = {id: group._id, name: group.name, inviter};
+      user.invitations.parties.push(user.invitations.party);
     } else {
       user.invitations.guilds.push({id: group._id, name: group.name, inviter});
     }