Editor mouse selection scrolling isn't smooth

[TylerLeonhardt]

Steps:

• have an editor with content that goes off the screen
• select some text and move your mouse in the direction of off screen

I expect a smooth scrolling experience where the editor smoothly scrolls to the right so I can select the text I want.

What actually happens is that it just jumps all the way to the end.

[rebornix]

This happened before we pushed fix b229eb5

[starball5]

Related Stack Overflow question: How to auto-scroll while selecting a long single line in VS Code with a mouse? Currently, it jumps to the end or beginning when reaching a screen edge

[thetotemguy]

Created #235174 to try fix this. That said, shift + scroll while highlighting is a slightly less ux friendly way to do it