macOS: Fix center window with fixed bounds size (#8475)

This PR fixes window showing up in the center of the monitor when
`center: true` option is provided.

The idea is to set the `window_wize` when creating the `window` using
`native_window.initWithContentRect_styleMask_backing_defer_screen_()`

Before: 

<img width="851" alt="SCR-20240227-qokf"
src="https://github.com/zed-industries/zed/assets/20229808/27494966-2e97-4771-8837-ccb6658ced78">

After:

<img width="1132" alt="SCR-20240227-qlmg"
src="https://github.com/zed-industries/zed/assets/20229808/439568da-d380-4331-8d19-cd501f211c4c">


Release Notes:

- N/A