Fixes #8672

Almost fully written by AI: https://ampcode.com/threads/T-86df68a3-578c-4a1c-91f3-788f8b8f0aae

I reviewed all the code.

Fixes #5256

This updates the macOS apprt to implement the `OPEN_URL` apprt action to
use the NSWorkspace APIs instead of the `open` command line utility.

As part of this, we removed the `ghostty_config_open` libghostty API and
instead introduced a new `ghostty_config_open_path` API that returns the
path to open, and then we use the `NSWorkspace` APIs to open it (same
function as the `OPEN_URL` action).

This makes it so `zig build run` can take arguments such as
`--config-default-files=false` or any other configuration. Previously,
it only accepted commands such as `+version`.

Incidentally, this also makes it so that the app in general can now take
configuration arguments via the CLI if it is launched as a new instance
via `open`. For example:

    open -n Ghostty.app --args --config-default-files=false

This previously didn't work. This is kind of cool.

To make this work, the libghostty C API was modified so that
initialization requires the CLI args, and there is a new C API to try to
execute an action if it was set.

This fixes an issue where pressing the red close button in a window or
the "x" button on a tab couldn't differentiate and would always close
the tab or close the window (depending on tab counts).

It seems like in both cases, AppKit triggers the `windowShouldClose`
delegate method on the controller, but for the close window case it
triggers this on ALL the windows in the group, not just the one
that was clicked.

I implemented a kind of silly coordinator that debounces
`windowShouldClose` calls over 100ms and uses that to differentiate
between the two cases.

This is recommended for macOS Tahoe and all standard menu items now have
associated images. This makes our app look more polished and native for
macOS Tahoe.

For icon choice, I tried to copy other native macOS apps as much as
possible, mostly from Xcode. It looks like a lot of apps aren't updated
yet. I'm absolutely open to suggestions for better icons but I think
these are a good starting point.

One menu change is I moved "reset font size" above "increase font size"
which better matches other apps (e.g. Terminal.app).