chore: Add departmentName to the return values of :agentId/departments endpoint

[KevLehman]

Proposed changes (including videos or screenshots)

• Adds a new departmentName key to the object returned from the :agentId/departments endpoint in Omnichannel.
• This will help to avoid some pagination problems on the UI (that will be fixed on another PR)

Issue(s)

https://rocketchat.atlassian.net/browse/SUP-623

Steps to test or reproduce

Further comments

Apparently the tests for this endpoint were not running, so those were fixed too. (Tests were made EE because of the limitation of departments on CE)

[dionisio-bot]

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[changeset-bot]

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Latest commit: 7de8b2f

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 59.40%. Comparing base (27bd512) to head (7de8b2f).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop   #32943      +/-   ##
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- Coverage    59.41%   59.40%   -0.01%     
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  Files         2541     2541              
  Lines        63187    63179       -8     
  Branches     14221    14219       -2     
===========================================
- Hits         37540    37533       -7     
  Misses       22931    22931              
+ Partials      2716     2715       -1     

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[KevLehman]

@MarcosSpessatto feel we can skip QA on this one as QA will be performed when the UI connects with it, wdyt?