[Screenshot] Add Chevereto API

[Neustradamus]

It is possible to add the Chevereto API?

• https://chevereto.com/
• https://github.com/chevereto/chevereto

ImgBB API is based on:

• https://api.imgbb.com/

[butyoutried]

screenshotplugin is deprecated and unmaintained now, this issue should be closed.