Changes editor scroll event registrations to subscriptions

Now, the unsubscribe call can also removes these subscriptions.
Ensures that the minimap always updates properly after a pane change

It still doesn’t position the minimap perfectly on scroll, but when
creating/deleting pane, the minimap stick to the content (wrapped or
unwrapped)
Avoid editor scrollview styles leaking on minimap
Fixes minimap scrolling issue

I’m pretty confident that the case is now closed.
The main issue was that we relied on the editor lines height.
But the returned values aren’t consistent after the pane count have
changed.