n-scrollbar support "scrollBy"

[pizberg]

This function solves the problem (这个功能解决的问题)

control scrollbar with mouse scroll, example, transmit y-scroll to x-scroll

Expected API (期望的 API)

scrollBy

[Sepush]

https://www.naiveui.com/en-US/os-theme/components/scrollbar#Scrollbar-Methods
use scrollTo

[pizberg]

https://www.naiveui.com/en-US/os-theme/components/scrollbar#Scrollbar-Methods use scrollTo

scrollTo is used to a fixed x/y position, but how to scroll a relative distance. e.g. scroll back -10px

[pizberg]

by the way, is there any build-in method to get current scrollbar x/y position and the whole width/height of the bar?
if above mentioned method is available, the relative scrolling also could be controlled.