Closes#10782
In some cases, during the auto-update process,
the update can fail and leave a dangling disk image in macOS. If the
auto-update fails again, a new dangling mounted volume will be left
behind. To avoid polluting the system with these dangling mounted disk
images,
implement [the `Drop`
trait](https://doc.rust-lang.org/std/ops/trait.Drop.html) for the
`MacOSUnmounter` struct. This will ensure that the disk image
is unmounted when the `install_release_macos` function exits regardless
of its result.
## How to test this locally
Unfortunately, I was a bit too lazy to find a smarter way to test this,
so I simply commented out a bunch of lines to emulate the auto-update
process. To replicate the linked issue (#10782), you can apply the
attached patch. Build the Zed binary and run it. The auto-update should
fail, leaving the dangling mounted disk image in the system:
```shell
>diskutil list
/dev/disk5 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +220.6 MB disk5
Physical Store disk4s1
1: APFS Volume Zed 190.6 MB disk5s1
```
Run the Zed binary again to create another mounted disk image:
```shell
>diskutil list
/dev/disk5 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +220.6 MB disk5
Physical Store disk4s1
1: APFS Volume Zed 190.6 MB disk5s1
/dev/disk7 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +220.6 MB disk7
Physical Store disk6s1
1: APFS Volume Zed 190.6 MB disk7s1
```
[simulate_zed_autoupdate.patch](https://github.com/user-attachments/files/16787955/simulate_zed_autoupdate.patch)
Please let me know if the fix is good; otherwise, I am happy to
implement it differently. Thanks!
Release Notes:
- Fixed#10782
ca2eb275de