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/auto_update/Cargo.toml

@@ -13,10 +13,12 @@ doctest = false
 anyhow.workspace = true
 client.workspace = true
 db.workspace = true
+editor.workspace = true
 gpui.workspace = true
 isahc.workspace = true
 lazy_static.workspace = true
 log.workspace = true
+markdown_preview.workspace = true
 menu.workspace = true
 project.workspace = true
 release_channel.workspace = true