Add option to customize the URLs of Web fonts written in CSS

**Describe the solution you'd like**
I would like to ask for a refurbishment so that I can change the URLs of Web fonts using BoxUIElements options (such as staticHost)

https://github.com/box/box-ui-elements/blob/e460bf23a16776a367e4cbb161568d72abc541dd/src/elements/common/fonts.scss

**Describe alternatives you've considered**
I think you can use techniques such as CSS custom properties, for example.

https://developer.mozilla.org/en-US/docs/Web/CSS/Using_CSS_custom_properties

**Additional context**
Since the URLs of Web fonts is written in CSS in the form of hardcoding, the BoxUIElements option is not effective, and I need to change the URL directly in CSS to change the URLs.

However, since this method requires downloading and saving CSS locally and changing the URLs in specified areas, we are concerned that this may cause problems when upgrading BoxUIElements in the future, such as the need for more time and effort, or the failure to change the URLs.