[REQ] Support for adding admins via command

[crashzk]

Support for adding/removing admins via commands, something like:

• !addadmin "STEAM_ID" "Admin Group/Flags" "Time"
• !removeadmin "STEAM_ID"

Time would be interesting to add so that the admins are automatically removed after the time we set expires.

Support for adding admin would be cumulative, that is, if I add admin twice for the same player, the time will be accumulated, that is, the first time I add 120 seconds, the second time I add admin before the time expires, add another 80 and add them all the time and update to 200.

[Pisex]

Was added in this update