Allow users to edit pages in Confluence without the Add page permission

Issue summary

1. Right now, if a user would like to share a page in a Space to be edited by another user, they will need to grant that user the Add Page permission.
2. This might not be the requirement of the user, as they would not want the user they're adding to add pages to a Space, but to only edit existing pages.
3. This ticket is a duplicate of the CONFSERVER-26522 suggestion ticket that was closed on 2012.

Current Behavior

1. User will need to have the Add Page permission in order to edit existing pages.

Suggested Behavior

1. Create a separate permission called Edit Page, that would allow users with the permission to edit pages in a Space without the permission to add or create more pages.