Group conversation permissions.

[STRO09]

Currently anyone can add/remove anyone from a group.

There is no logic for permissions and admin as of now.

Changes Needed Currently:
(admin is stored as per the user who created the group, but the api allows any user to make changes so does the UI )

1. UI changes to make the group info modal view only and hide the buttons for non-admin members.
   Changes would be needed in : assets/js/dashboardfunctions.js
2. API restrictions to not allow non-admin users to add or remove users. changes needed in : routes/conversationRoutes.js (a new file can be created named groupMiddleware and a function checkGroupAdminAccess)

(Optional) : The modal is very basic for now, UI can be improved.