Add action to open release notes locally (#8173)

Fixes: https://github.com/zed-industries/zed/issues/5019

zed.dev PR: https://github.com/zed-industries/zed.dev/pull/562

I've been wanting to be able to open release notes in Zed for awhile,
but was blocked on having a rendered Markdown view. Now that that is
mostly there, I think we can add this. I have not removed the `auto
update: view release notes` action, since the Markdown render view
doesn't support displaying media yet. I've opted to just add a new
action: `auto update: view release notes locally`. I'd imagine that in
the future, once the rendered view supports media, we could remove `view
release notes` and `view release notes locally` could replace it.
Clicking the toast that normally is presented on update
(https://github.com/zed-industries/zed/issues/7597) would show the notes
locally.

The action works for stable and preview as expected; for dev and
nightly, it just pulls the latest stable, for testing purposes.

I changed the way the markdown rendered view works by allowing a tab
description to be passed in.

For files that have a name, it will use `Preview <name>`:

<img width="1496" alt="SCR-20240222-byyz"
src="https://github.com/zed-industries/zed/assets/19867440/a0ef34e5-bd6d-4b0c-a684-9b09d350aec4">

For untitled files, it defaults back to `Markdown preview`:

<img width="1496" alt="SCR-20240222-byip"
src="https://github.com/zed-industries/zed/assets/19867440/2ba3f336-6198-4dce-8867-cf0e45f2c646">

Release Notes:

- Added a `zed: view release notes locally` action
([#5019](https://github.com/zed-industries/zed/issues/5019)).


https://github.com/zed-industries/zed/assets/19867440/af324f9c-e7a4-4434-adff-7fe0f8ccc7ff

crates/zed/src/zed.rs

@@ -58,10 +58,10 @@ actions!(
         OpenDefaultKeymap,
         OpenDefaultSettings,
         OpenKeymap,
-        OpenTasks,
         OpenLicenses,
         OpenLocalSettings,
         OpenLog,
+        OpenTasks,
         OpenTelemetryLog,
         ResetBufferFontSize,
         ResetDatabase,
@@ -401,9 +401,9 @@ fn initialize_pane(workspace: &mut Workspace, pane: &View<Pane>, cx: &mut ViewCo
 }
 
 fn about(_: &mut Workspace, _: &About, cx: &mut gpui::ViewContext<Workspace>) {
-    let app_name = ReleaseChannel::global(cx).display_name();
+    let release_channel = ReleaseChannel::global(cx).display_name();
     let version = env!("CARGO_PKG_VERSION");
-    let message = format!("{app_name} {version}");
+    let message = format!("{release_channel} {version}");
     let detail = AppCommitSha::try_global(cx).map(|sha| sha.0.clone());
 
     let prompt = cx.prompt(PromptLevel::Info, &message, detail.as_deref(), &["OK"]);