Closes #20762

Release Notes:

- N/A

---

Enable MSAA for Anti-Aliasing to Path (`cx.paint_path`) for drawing a
better vector graphics.

```bash
cargo run -p gpui --example gradient --features macos-blade
cargo run -p gpui --example gradient

cargo run -p gpui --example painting --features macos-blade
cargo run -p gpui --example painting
```

**Before**

<img width="1089" alt="image"
src="https://github.com/user-attachments/assets/0ae7240f-4ba9-4ef5-896c-e436c1282770"
/>

**After**

<img width="944" alt="image"
src="https://github.com/user-attachments/assets/71a07ae8-be54-452c-aacc-b8cec1f810c0"
/>

## TODO

- [x] Support Metal and Blade.
- [x] Detect system support to set up sample count.
- [x] Fix extra lines between Path vertices wait #22808 to merge.

Ref https://github.com/kvark/blade/pull/213

Ask @kvark to review.

I am not sure if there is anything I missed. I modified it according to
the
[particle](https://github.com/kvark/blade/tree/main/examples/particle)
example of Blade project. But the difference is that after the first
MSAA render, I did not do it a second time, I tested it and found it was
not necessary.