[FIX] Groups endpoints permission validations (#13994)
[FIX] Groups endpoints permission validations (#13994)

* Fix find groups to be able to use the groups endpoints with discussions

* Improve private groups REST permission checkings

* Don't use find from canAccessRoom

VoiSmart/Rocket.Chat,subesokun/Rocket.Chat,subesokun/Rocket.Chat,inoio/Rocket.Chat,Sing-Li/Rocket.Chat,subesokun/Rocket.Chat,subesokun/Rocket.Chat,Sing-Li/Rocket.Chat,Sing-Li/Rocket.Chat,4thParty/Rocket.Chat,inoio/Rocket.Chat,4thParty/Rocket.Chat,4thParty/Rocket.Chat,inoio/Rocket.Chat,VoiSmart/Rocket.Chat,Sing-Li/Rocket.Chat,VoiSmart/Rocket.Chat,4thParty/Rocket.Chat