For ports with a root process we should show a placeholder if we can't find the command line

[alexr00]

Now that we try to find root ports (#4654), we do know that a process is listening on a port even if we can't access the command line or process ID.

We should show placeholder text in the "Running Process" column, and show the "filled circle" icon for root ports even if we can't read the command line.

[alexr00]

To verify:

1. Connect to a linux remote and make sure that "remote.autoForwardPortsSource": "process".
2. Start a process as root and doesn't have the port number in the command line (ex. sudo npx http-server).
3. Open the Ports view and forward the port from step 2.
4. Verify that the new forwarded port has a filled in circle as its icon. Verify that the "Running Process" column reads "Command line unavailable).
5. Kill the process from step 2.
6. Verify that your forwarded port has an empty circle as its icon. Verify that the "Running Process" column is empty.
7. Repeat steps 2-4.