feat: add welcomer cog for greeting new members

Introduces a simple cog that welcomes new users via customizable messages in designated channels, enhancing community engagement.

Handles channel selection with fallbacks and includes error resilience for permission issues.

welcomer/info.json

@@ -0,0 +1,14 @@
+{
+  "author": [ "unstableCogs" ],
+  "install_msg": "Thank you for installing the Welcomer cog!",
+  "name": "Welcomer",
+  "short": "A simple cog to welcome new users.",
+  "description": "Greets new members in a designated channel with a customizable message. This cog is part of the Unified Bot Suite.",
+  "tags": [
+    "welcome",
+    "utility",
+    "greeting"
+  ],
+  "requirements": [],
+  "end_user_data_statement": "This cog does not persistently store any end user data."
+}