Chore: Add node-pty

node-pty will be used to provider a better interactive terminal.
It's required to have colors and progress bars from bitbake.
Explanation: microsoft/vscode#155444 (comment)

However, VSCode uses electron which has it's own npm
NODE_MODULE_VERSION. I had to use `@electron/rebuild` to match the
version. I wonder if it would break when VSCode updates electron.

There are discussions which failed to provide other workarounds
(we don't use webpack yet):
 - microsoft/node-pty#582
 - microsoft/vscode#658

The format of the files and package-lock.json where updated by npm
install.