Remove Chat (#37789)

At RustConf we were demo'ing zed, and it continually popped open the
chat panel.

We're usually inured to this because the Chat panel doesn't open unless
a Guest
is in the channel, but it made me sad that we were showing a long stream
of
vacuous comments and unresponded to questions on every demo screen.

We may bring chat back in the future, but we need more thought on the
UX, and
we need to rebuild the backend to not use the existing collab server
that we're
trying to move off of.

Release Notes:

- Removed the chat feature from Zed (Sorry to the 5 of you who use this
on the regular!)

docs/src/visual-customization.md

@@ -94,7 +94,6 @@ To disable this behavior use:
   // "project_panel": {"button": false },
   // "outline_panel": {"button": false },
   // "collaboration_panel": {"button": false },
-  // "chat_panel": {"button": "never" },
   // "git_panel": {"button": false },
   // "notification_panel": {"button": false },
   // "agent": {"button": false },
@@ -554,13 +553,6 @@ See [Terminal settings](./configuring-zed.md#terminal) for additional non-visual
   },
   "show_call_status_icon": true,  // Shown call status in the OS status bar.
 
-  // Chat Panel
-  "chat_panel": {
-    "button": "when_in_call",     // status bar icon (true, false, when_in_call)
-    "dock": "right",              // Where to dock: left, right
-    "default_width": 240          // Default width of the chat panel
-  },
-
   // Notification Panel
   "notification_panel": {
     // Whether to show the notification panel button in the status bar.