Do more on channel join (#7268)

This change makes it so that if you are the first to join a channel,
your project is automatically shared.

It also makes it so that if you join a channel via a link and there are
no shared projects, you open the notes instead of an empty workspace
with nothing.

This is to try and address the discoverability of project sharing: we've
had
two reviews that have talked about channels, but not talked about
sharing
projects into them, which makes me suspect they didn't know about the
feature.

Release Notes:

- Added a setting `share_on_join` (defaulting to true). When set, and
you join an empty channel, your project is automatically shared.

crates/collab_ui/src/collab_panel.rs

@@ -40,7 +40,7 @@ use util::{maybe, ResultExt, TryFutureExt};
 use workspace::{
     dock::{DockPosition, Panel, PanelEvent},
     notifications::{DetachAndPromptErr, NotifyResultExt, NotifyTaskExt},
-    Workspace,
+    OpenChannelNotes, Workspace,
 };
 
 actions!(
@@ -69,6 +69,19 @@ pub fn init(cx: &mut AppContext) {
         workspace.register_action(|workspace, _: &ToggleFocus, cx| {
             workspace.toggle_panel_focus::<CollabPanel>(cx);
         });
+        workspace.register_action(|_, _: &OpenChannelNotes, cx| {
+            let channel_id = ActiveCall::global(cx)
+                .read(cx)
+                .room()
+                .and_then(|room| room.read(cx).channel_id());
+
+            if let Some(channel_id) = channel_id {
+                let workspace = cx.view().clone();
+                cx.window_context().defer(move |cx| {
+                    ChannelView::open(channel_id, workspace, cx).detach_and_log_err(cx)
+                });
+            }
+        });
     })
     .detach();
 }