[MIRROR] Overhauls discord verification system (#588)

* Overhauls discord verification system (#53289)

This completely replaces the previous verification system, for one that
will interoperate with a discord redbot instance that uses the cogs
located at you github.com/optimumtact/orangescogs

This cuts out several steps in the system, but it also leaves alone the
existing notify system (which just uses a file list of discord ids) as a
record of who to notify

SQL changes required for the new database system

Version 5.10, 7 August 2020, by oranges

Changes how the discord verification process works.
Adds the discord_links table, and migrates discord id entries from
player table to the discord links table in a once off operation and then
removes the discord id on the player table

The user connects to any tg server, and uses the "Verify Discord
Account" verb, this generates a six word one time use token, with a 4
hour time validity period (defined as 4 hours from the timestamp value)
in the discord links table.

This one time token, and the ckey of the user are stored in
discord_links

At this point the entire DM side is done, this is all it does

* Overhauls discord verification system

Co-authored-by: oranges <email@oranges.net.nz>

code/modules/admin/admin_verbs.dm

@@ -75,7 +75,6 @@ GLOBAL_PROTECT(admin_verbs_admin)
 	/client/proc/resetasaycolor,
 	/client/proc/toggleadminhelpsound,
 	/client/proc/respawn_character,
-	/client/proc/discord_id_manipulation,
 	/datum/admins/proc/open_borgopanel
 	)
 GLOBAL_LIST_INIT(admin_verbs_ban, list(/client/proc/unban_panel, /client/proc/ban_panel, /client/proc/stickybanpanel))