Explore running an xterm.js node target on the server

[Tyriar]

Basic idea is to run pty output through a lightweight xterm.js instance on the server to enable better terminal session restoration.

Related links:

• Create a node.js target for xterm.js xtermjs/xterm.js#2749
• Create a node.js target for xterm.js xtermjs/xterm.js#3212
• Move API view classes under common/public xtermjs/xterm.js#3214
• Feature/xterm addon serialize restore layout and cursor xtermjs/xterm.js#3101