react-md-editor: Rendering the editor breaks the current body overflow

Hi,

First of all, thanks so much for this amazing lib! 🙌

I just found out that This line is causing problems because it changes the body styles directly by setting the overflow to either initial or hidden.

https://github.com/uiwjs/react-md-editor/blob/master/src/components/Toolbar/index.tsx#L49

Imagine we have a fixed body layout and we always want the overflow to be hidden… we can’t basically use this component.

I could open a PR to fix it but I don’t know really which approach would be better… any preference?

Thanks!