Add a `snapOnOutput` setting

[sms20180130]

Windows Terminal version

1.21.3231.0

Windows build number

19044.2965

Other Software

No response

Steps to reproduce

open Terminal
ping -t 8.8.8.8
see the reply lines fill up window
hover mouse to window and wheel up
the new reply line do not display automatically, unless wheel down to last line

Expected Behavior

open cmd.exe
ping -t 8.8.8.8
see the reply lines fill up window
hover mouse and wheel up
auto jumps (force) to the new line despite mouse wheel up or not

Actual Behavior

I know so-called "bug behavior" is normal for linux or others systems, but I really need something act as the original cmd.exe does, perhaps I missed some configs?thanks

[DHowett]

Thanks! I'm linking this up to #6106.