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/markdown_preview/src/markdown_preview_view.rs

@@ -6,7 +6,7 @@ use gpui::{
     IntoElement, ListState, ParentElement, Render, Styled, View, ViewContext, WeakView,
 };
 use ui::prelude::*;
-use workspace::item::Item;
+use workspace::item::{Item, ItemHandle};
 use workspace::Workspace;
 
 use crate::{
@@ -22,6 +22,7 @@ pub struct MarkdownPreviewView {
     contents: ParsedMarkdown,
     selected_block: usize,
     list_state: ListState,
+    tab_description: String,
 }
 
 impl MarkdownPreviewView {
@@ -34,8 +35,9 @@ impl MarkdownPreviewView {
 
             if let Some(editor) = workspace.active_item_as::<Editor>(cx) {
                 let workspace_handle = workspace.weak_handle();
+                let tab_description = editor.tab_description(0, cx);
                 let view: View<MarkdownPreviewView> =
-                    MarkdownPreviewView::new(editor, workspace_handle, cx);
+                    MarkdownPreviewView::new(editor, workspace_handle, tab_description, cx);
                 workspace.split_item(workspace::SplitDirection::Right, Box::new(view.clone()), cx);
                 cx.notify();
             }
@@ -45,6 +47,7 @@ impl MarkdownPreviewView {
     pub fn new(
         active_editor: View<Editor>,
         workspace: WeakView<Workspace>,
+        tab_description: Option<SharedString>,
         cx: &mut ViewContext<Workspace>,
     ) -> View<Self> {
         cx.new_view(|cx: &mut ViewContext<Self>| {
@@ -119,12 +122,17 @@ impl MarkdownPreviewView {
                 },
             );
 
+            let tab_description = tab_description
+                .map(|tab_description| format!("Preview {}", tab_description))
+                .unwrap_or("Markdown preview".to_string());
+
             Self {
                 selected_block: 0,
                 focus_handle: cx.focus_handle(),
                 workspace,
                 contents,
                 list_state,
+                tab_description: tab_description.into(),
             }
         })
     }
@@ -188,11 +196,13 @@ impl Item for MarkdownPreviewView {
             } else {
                 Color::Muted
             }))
-            .child(Label::new("Markdown preview").color(if selected {
-                Color::Default
-            } else {
-                Color::Muted
-            }))
+            .child(
+                Label::new(self.tab_description.to_string()).color(if selected {
+                    Color::Default
+                } else {
+                    Color::Muted
+                }),
+            )
             .into_any()
     }