Show current plan in user menu (#15513)

This PR updates the user menu to show the user's current plan.

Also adds a new RPC message to send this information down to the client
when Zed starts.

This is behind a feature flag.

Release Notes:

- N/A

---------

Co-authored-by: Max <max@zed.dev>

crates/zed/src/zed.rs

@@ -47,7 +47,7 @@ use workspace::{
     open_new, AppState, NewFile, NewWindow, OpenLog, Toast, Workspace, WorkspaceSettings,
 };
 use workspace::{notifications::DetachAndPromptErr, Pane};
-use zed_actions::{OpenBrowser, OpenSettings, OpenZedUrl, Quit};
+use zed_actions::{OpenAccountSettings, OpenBrowser, OpenSettings, OpenZedUrl, Quit};
 
 actions!(
     zed,
@@ -422,6 +422,12 @@ pub fn initialize_workspace(app_state: Arc<AppState>, cx: &mut AppContext) {
                     );
                 },
             )
+            .register_action(
+                |_: &mut Workspace, _: &OpenAccountSettings, cx: &mut ViewContext<Workspace>| {
+                    let server_url = &client::ClientSettings::get_global(cx).server_url;
+                    cx.open_url(&format!("{server_url}/settings"));
+                },
+            )
             .register_action(
                 move |_: &mut Workspace, _: &OpenTasks, cx: &mut ViewContext<Workspace>| {
                     open_settings_file(