[Bug] Scrollbars are hard to grab due to resizer area covering most of the scrollbar

### Bug Description

In eg. the Sidebar or in a Document, when you need to scroll and you want to use your mouse to grab the scrollbar for more refined control or faster scroll speed, it's hard to grab them because eg. the sidebar resizer area covers some of the scrollbar, and it's the same in a document where the window resizer also covers some of the scrollbar.

### How to Reproduce

In a very long document, try to use the scrollbar.

In a sidebar with a lot of nested views, try to use the scrollbar.

### Expected Behavior

Easy to grab and use the scrollbars using cursor

### Operating System

all

### AppFlowy Version(s)

0.7.2

### Screenshots

_No response_

### Additional Context

_No response_