chat panel ++ (#4044)

- Update chat panel with current channel
- Open chat panel for guests
- Open chat when joining a channel with guests
- Some tweaks for chat panels
- Don't lose focus on default panel state
- Make chat prettier (to my eyes at least)
- Fix multiple mentions in one message
- Show a border when scrolled in chat
- Fix re-docking chat panel
- Move settings subscription to dock

[[PR Description]]

Release Notes:

- Opens chat by default when joining a public channel
- Improves chat panel UI

crates/project_panel/src/project_panel.rs

@@ -1,6 +1,6 @@
 pub mod file_associations;
 mod project_panel_settings;
-use settings::{Settings, SettingsStore};
+use settings::Settings;
 
 use db::kvp::KEY_VALUE_STORE;
 use editor::{scroll::autoscroll::Autoscroll, Cancel, Editor};
@@ -246,18 +246,6 @@ impl ProjectPanel {
             };
             this.update_visible_entries(None, cx);
 
-            // Update the dock position when the setting changes.
-            let mut old_dock_position = this.position(cx);
-            ProjectPanelSettings::register(cx);
-            cx.observe_global::<SettingsStore>(move |this, cx| {
-                let new_dock_position = this.position(cx);
-                if new_dock_position != old_dock_position {
-                    old_dock_position = new_dock_position;
-                    cx.emit(PanelEvent::ChangePosition);
-                }
-            })
-            .detach();
-
             this
         });