terminal: Add scrollX and scrollY

[MrcSnm]

While playing with terminal, main problem with moveTo is that when using PowerShell, the moveTo is relative to the current powershell scroll.

That means I would need to moveTo(0, t.cursorY - t.scrollY). Though on cmd, there's no need since it doesn't offset by scroll.
Although I could simply say "do not use powershell", the default terminal on VSCode is powershell so it is quite important to have that working.