[EE] Omnichannel monitors not authorized to view departments

[renatobecker]

By design, users with livechat-monitors role might be able to deal with all departments associated with units they're monitoring, but currently, Omnichannel Monitors are not authorized to view any department.
This is happening because the permission manage-livechat-departments is not granted to livechat-monitors role.

Proposed changes (including videos or screenshots)

Issue(s)

Steps to test or reproduce

Further comments

[murtaza98]

@renatobecker This PR looks good. I tested the above scenario with and a without this PR. earlier the monitor was getting a Unauthorized error while trying to view the departments, however with this fix, the monitor is able to see all the departments.