Users can clone the same channel by just changing the letter case

Description:

Any user can clone any channel as long as they change the letter case.
As example, if I create a channel named #Portugal, another user can create #portugal, another one can create #PoRtUgAl

Steps to reproduce:

1. Create a channel named #SpaceShip
2. Create the same channel but this time names #spaceship
3. Both channels will coexist, which doesn't make much sense since the name is the same except the letter casing.

Expected behavior:

As long as the channel name is the same, the letter casing should be ignored and the cloned channel shouldn't be created.

Actual behavior:

ANY channel can be cloned more than once as long as the letter casing differs.

Server Setup Information:

• Version of Rocket.Chat Server: 3.2.2
• Operating System: Ubuntu 19.10
• Deployment Method: tar
• Number of Running Instances: 1
• DB Replicaset Oplog: enabled (rs01)
• NodeJS Version: 12.16.1
• MongoDB Version: 4.0.18

Client Setup Information

• Desktop App or Browser Version: Mobile: 4.7.0.17188 | Desktop: Firefox 7.60
• Operating System: Mobile: Android 9 | Desktop: Ubuntu 20.04

Additional context

Relevant logs:

No relevant logs to show (I believe)

Start by reproducing the issue through the channel-creation flow: create #SpaceShip, then try #spaceship and #SpAcEsHiP. Check how channel names are validated and persisted with the stated MongoDB setup; done means differently cased versions of the same name cannot coexist.