uid in is_writable () always zero when mount SSH share except "sftp only" connections

### What Happened?

uid variable in is_writable () method (libcore/File.vala) always zero, except when the user connect "sftp only" server (_ForceCommand internal-sftp_).

### Steps to Reproduce

1. Watch uid in is_writable () method and run io.elementary.files
2. Connect to a SSH server with non "sftp only" user
3. Connect to a SSH server with "sftp only" user

### Expected Behavior

When you connect with non "sftp only" user, the value of uid is always zero.
When you connect with "sftp only" user, the value of uid is always the real user id.

### OS Version

6.x (Odin)

### Software Version

Compiled from git

### Log Output

_No response_

### Hardware Info

_No response_