`\x7f` is always converted to `\x08`/`\b` on Windows

Environment details

OS: Windows 10
OS version: Microsoft Windows [Version 10.0.19045.2364]
node-pty version: main branch and 0.10.0

Issue description

When writing \x7f on Windows, the input will always be converted to \x08. It is unclear where this transform is occurring. To reproduce,

// relative to examples/fork/index.js
const pty = require('../..');

// reproduces with both cmd.exe and powershell.exe
const ptyProcess = pty.spawn('cmd.exe', [], {
  name: '...',
  cols: 80,
  rows: 26,
  cwd: process.env.USERPROFILE,
  // reproduces regardless of this value
  useConpty: true,
});

ptyProcess.onData(data => process.stdout.write(data));

ptyProcess.write('python -c "import msvcrt; print(msvcrt.getch())"\r');
ptyProcess.write('\x7f');

process.on('exit', () => ptyProcess.kill());
setTimeout(() => process.exit(), 500);

This issue appears to be independent of the shell and is reproducible using both winpty and conpty.

microsoft / node-pty

`\x7f` is always converted to `\x08`/`\b` on Windows #575

Environment details

Issue description