Add horizontal scrolling using vertical scroll wheel

### Problem I have

I use Phanpy on a typical desktop with a mouse that only has a vertical scroll wheel. Scrolling down is an enjoyable experience - I just scroll the wheel down. But for the post groups (carousels?) Phanpy makes, I have to use the left and right buttons in the top right, which is less enjoyable.

### Solution I'd like

I propose adding horizontal scrolling using a vertical scroll wheel for these carousels. The functionality I imagine is you place your mouse over the arrows and scroll up or down and the carousel scrolls left or right, respectively.

### Alternatives considered

Another option is to implement this if the mouse is in that carousel at all but that could interrupt natural scrolling too often for the average user.

### Other

_No response_