Rosetta exposed to Linux guests have no SELinux context, breaking container workflows

**Describe the issue**
Rosetta exposed to Linux guests are not given SELinux contexts, and it is impossible to manually apply any because the virtiofs directory is functionally read-only (can be mounted rw but errors out with `Operation not permitted` when manually running `chcon`).

This affects me when running a SELinux-enforcing distro and attempting to run a container with `--arch=amd64`.

To reproduce:
- Start a VM with a SELinux-enforcing distro (I used RHEL but Fedora should work as well) using Virtualization, with Rosetta enabled
- Configure Rosetta as [documented](https://docs.getutm.app/advanced/rosetta/)
- Fedora and derivatives may need to do the `update-binfmts` step manually with `echo ':rosetta:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x3e\x00:\xff\xff\xff\xff\xff\xfe\xfe\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/media/rosetta/rosetta:PCF' | sudo tee /proc/sys/fs/binfmt_misc/register`
- Install Podman
- Start a container with the amd64 arch and run some command in it
- `podman run --arch=amd64 quay.io/centos/centos:stream10 uname -m` for example

Expected result:

```
x86_64
```

Actual result: no output, exit code 139, `journalctl -b -et setroubleshoot` reports a violation

```
Source Context: system_u:system_r:container_t:s0:c986,c993
Target Context: system_u:system_r:unlabeled_t:s0
Target Objects: /media/rosetta/rosetta [ file ]
```

**Configuration**
* UTM Version: 4.7.5 (118)
* macOS Version: 26.5 (25F71)
* Mac Chip (Intel, M1, ...): M4

**Crash log**
Does not apply.

**Debug log**
Does not apply imo but I can provide if required.

**Upload VM**
Does not apply imo but I can provide if required.