Add mouse wheel scroll multiplier.

[teropentis64]

Is your feature request related to a problem? Please describe.
Ghidra sensitivity to mouse wheel scroll is way higher than every other app.
It may seem a little issue when user is equipped with standard mouse wheel but using Ghidra on touchpad (e.g. in class on a MacBook) may be a little distracting.
It's not like it's a bit faster, you really have to be careful with hand gestures not to miss the next jmp branch.

Describe the solution you'd like
Just add scroll sensitivity multiplier or if it's easier to implement, try to match the system feeling.

Additional context
The issue is existent in macOS since I remember. It's not a bug but implementation. I haven't checked if Windows is the same.