Possibility to disable the invite users to Jira button from Slack.

It is a problem when users that don't need access to Jira are being invited to it, turning very hard the administration task for those who have a lot of users inviting individuals from outside of the organization or (even inside the organization) that should not have access to the system.

With the possibility to disable this option, the Administrators will be able to control if they want their users to invite other users or not.