Xterm 5 - bellSound/bellStyle options have been removed

[javier-godoy]

bellSound and bellStyle options have been removed from XTerm.js 5, in favor of Terminal.onBell API (xtermjs/xterm.js#3941) which is already available in XTerm.js 4.19.0

// before 5.0.0
term = new Terminal({
  bellStyle: 'sound'
});

// after 5.0.0
term = new Terminal();
term.onBell(() => {
  // Play a sound
});