feat: support virtualedit

[yehuohan]

This PR allows hop to jump to anywhere you want with virtualedit used, even there is a blank cell like the picture showed below.
So any hop-regex/extension can supports virtualedit via only provide extra Cursor.off and Cursor.virt.
Currently hint_vertical and hint_lines can jump to blank cells when virutaledit = insert/block/all.

[smoka7]

Thanks for your contribiution. I'm not sure about adding this. It Doesn't seem a usefull feature and it adds more complexity to plugin.
I'm open to feedback from you or other users who might have insights to share.

[yehuohan]

Thank your reply.
This PR does introduce complexity on computing row and col with virtualedit enabled.
Actually I think only hint_vertical gets improved a lot for virtualedit users currently.
And hope there will be more extensions can make use of this feature. :)