gpui: Fix cx.bounds, cx.open_window position on macOS (#14044)
Release Notes:
- gpui: Fixed `cx.bounds` method to get correct `y` position on macOS.
- gpui: Fixed `cx.open_window` position when macOS Dock is existed.
- Fixed call notification and reopen window position.
## Before
https://github.com/zed-industries/zed/assets/5518/ab925779-4253-4b27-9084-01023888087f
## After
<img width="533" alt="image"
src="https://github.com/zed-industries/zed/assets/5518/142e9aaa-ae82-4a72-9acf-04097c545bf0">
https://github.com/zed-industries/zed/assets/5518/8793824a-8b74-4913-8204-7b39649aeeed
---
The case is I have made a Popover by use child window, the coordinate of
the window is always can't placement a right position.
So, I make this example to test the `cx.bounds` and set bounds to
window.
---
By this test, is the `cx.bounds` have a bug?
For example the **Top Left** window, we give it origin (150,150), but it
`cx.bounds()` returns (150,262)
> On the window label, middle line is the `bounds` that we set to the
window, last line is `cx.bounds()` result.
Display 1:
<img width="1512" alt="CleanShot 2024-07-10 at 14 52 26@2x"
src="https://github.com/zed-industries/zed/assets/5518/3adf9e79-f237-431a-a72b-02face7b2361">
---
Or is there something I missed. Is it correct to use `cx.bounds` method
to get the bounds of the current window?
At the same time, I also found that when there are multiple screens, the
information obtained by cx.bounds is very different on different
screens, and it seems that the origin is not relative to the screen.
Display 2:
<img width="2560" alt="SCR-20240710-nkmq"
src="https://github.com/zed-industries/zed/assets/5518/d87d4151-0562-4bf8-b3b3-5da3b4d09d82">
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