MotD (#13655)

* MOTD

* Message of the Day

* Pretty sure the tests aren't me. Let's check.

* Update Content.Shared/CCVar/CCVars.cs

Co-authored-by: AJCM-git <60196617+AJCM-git@users.noreply.github.com>

* command dependencies and moving MOTD to its own system

* Some doc comments

* Let's try those tests again

* More doc comments, most of the github reviews, and aliases for get-motd and set-motd

* Clear test MOTD

* Localized motd commands and completion hints

* Makes set-motd only show up in the alias command if the player has access to it.

---------

Co-authored-by: AJCM-git <60196617+AJCM-git@users.noreply.github.com>

Content.Server/Motd/GetMOTDCommand.cs

@@ -0,0 +1,20 @@
+using Content.Shared.Administration;
+using Robust.Shared.Console;
+
+namespace Content.Server.Motd;
+
+/// <summary>
+/// A command that can be used by any player to print the Message of the Day.
+/// </summary>
+[AnyCommand]
+public sealed class GetMotdCommand : LocalizedCommands
+{
+    [Dependency] private readonly IEntityManager _entityManager = default!;
+
+    public override string Command => "get-motd";
+    
+    public override void Execute(IConsoleShell shell, string argStr, string[] args)
+    {
+        _entityManager.EntitySysManager.GetEntitySystem<MOTDSystem>().TrySendMOTD(shell);
+    }
+}