Generated Coder SSH config contains invalid/unknown user permissions

Remote SSH connections failing on Windows because the SSH config file generated by the Coder extension has invalid file permissions.

### Error

With latest vscode plugin Remote SSH fails with the following message:

```
Bad permissions. Try removing permissions for user:
UNKNOWN\UNKNOWN (S-1-5-21-354618XXXX-405751XXXX-XXXXXXX-XXXXXXXXXX)
on file C:/Users//AppData/Roaming/coder.coder-remote/ssh/vscode--xxxxx.de.conf.

Bad owner or permissions on
C:\Users\\AppData\Roaming\coder.coder-remote\ssh\vscode--coder.zugang
```

### Workaround

Downgrading the Coder VS Code extension to version 1.15.2 resolves the issue for me.

With version 1.15.2, I can use the Coder-generated SSH configuration directly from my normal SSH config file, and VS Code Remote SSH connects successfully.

Start by reproducing the Windows Remote SSH failure with the generated file at C:/Users//AppData/Roaming/coder.coder-remote/ssh/vscode--xxxxx.de.conf and compare it with extension version 1.15.2. Trace where the Coder VS Code extension creates its SSH configuration, then verify that the generated file has valid owner and permissions and that VS Code Remote SSH connects successfully.

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