electerm: Path traversal in editWithSystemEditor temp file path via unsanitized SFTP filename

electerm is an open-sourced terminal/ssh/sftp/telnet/serialport/RDP/VNC/Spice/ftp client. Prior to 3.15.120, electerm allows a malicious SFTP server to write attacker-controlled content outside the temporary directory because the server-controlled filename name used by editWithSystemEditor in src/client/components/sftp/file-item.jsx is interpolated into path.resolve without sanitization. This issue is fixed in version 3.15.120.