Enable Blade on MacOS via "macos-blade" feature (#7669)

Depends on https://github.com/zed-industries/font-kit/pull/2 and
https://github.com/kvark/blade/pull/77

This change enables Blade to be also used on MacOS. It will also make it
easier to use it on Windows.

What works: most of the things. Zed loads as fast and appears equally
responsive to the current renderer.
<img width="306" alt="Screenshot 2024-02-11 at 12 09 15 AM"
src="https://github.com/zed-industries/zed/assets/107301/66d82f45-5ea2-4e2b-86c6-5b3ed333c827">

Things missing:
- [x] video streaming. ~~Requires a bit of plumbing on both Blade and
Zed sides, but all fairly straightforward.~~
  -  verified with a local setup
- [x] resize. ~~Not sure where exactly to hook up the reaction on the
window size change. Once we know where, the fix is one line.~~
- [ ] fine-tune CA Layer
- this isn't a blocker for merging the PR, but it would be a blocker if
we wanted to switch to the new path by default
- [ ] rebase on latest, get the dependency merged (need review/merge of
https://github.com/zed-industries/font-kit/pull/2!)

Update: I implemented resize support as well as "surface" rendering on
the Blade path (which will be useful on Linux/Windows later on). I
haven't tested the latter though - not sure how to get something
streaming. Would appreciate some help! I don't think this should be a
blocker to this PR, anyway.

The only little piece that's missing for the Blade on MacOS path to be
full-featured is fine-tuning the CALayer configuration. Zed does a lot
of careful logic in configuring the layer, such as switching the
"present with transaction" on/off intermittently, which Blade path
doesn't have yet.

Release Notes:
- N/A

---------

Co-authored-by: Mikayla <mikayla@zed.dev>

crates/gpui/src/gpui.rs

@@ -60,8 +60,9 @@
 //! and will be publishing more guides to GPUI on our [blog](https://zed.dev/blog).
 
 #![deny(missing_docs)]
-#![allow(clippy::type_complexity)]
-#![allow(clippy::collapsible_else_if)]
+#![allow(clippy::type_complexity)] // Not useful, GPUI makes heavy use of callbacks
+#![allow(clippy::collapsible_else_if)] // False positives in platform specific code
+#![allow(unused_mut)] // False positives in platform specific code
 
 #[macro_use]
 mod action;