SS14-17313 Chatfactor: Chat Censorship Systems (#25908)

* SS14-17313 Chat Censorship Systems

Adds some systems to manage chat censorship:

1. No-op: does nothing
2. SimpleCensor: a regex-free censor with a variety of rules to use
3. RegexCensor: a censor that uses regex.

This exposes a singleton backed by a builder pattern (ChatCensor) that
is set up, probably during the code init phase, and then globally available
for your censorship needs.

* Migrate to Shared

* Add a reset function to the builder.

* Resolve PJB's feedback; add unit tests

Content.Shared/Chat/V2/Moderation/RegexCensor.cs

@@ -0,0 +1,15 @@
+using System.Text.RegularExpressions;
+
+namespace Content.Shared.Chat.V2.Moderation;
+
+public sealed class RegexCensor(Regex censorInstruction) : IChatCensor
+{
+    private readonly Regex _censorInstruction = censorInstruction;
+
+    public bool Censor(string input, out string output, char replaceWith = '*')
+    {
+        output = _censorInstruction.Replace(input, replaceWith.ToString());
+
+        return !string.Equals(input, output);
+    }
+}