Add spectacle support

[JoshuaVandaele]

Is your feature request related to a problem? Please describe.
XBackBone does not have native support for integrating with Spectacle (the screenshot utility for KDE desktop), so users of XBackBone on KDE desktop environments are unable to easily capture and share screenshots with their default screenshot utility

Describe the solution you'd like
KDE applications like Spectacle (Screenshot utility), Dolphin (File manager), and Okular (document viewer) all support sharing files via "Share..."

Spectacle even supports sharing to Imgur and it puts the URL in the clipboard, I think XBackBone could create something like that.

Additional context
I think this: https://develop.kde.org/docs/apps/dolphin/service-menus/ is a good starting point? I'm not sure though, I don't know much about how this all works, here are some examples of plugins that already do something alike to this if this helps:
(from https://userbase.kde.org/Spectacle)

[sergix44]

Thanks for the input, it would be good to be able to support some well mantained clients for linux

[SrS2225a]

I think it is a neat idea. Another possible solution is to create a purpose plugin which is supposed to integrate services and actions on any application without having to implement them specifically, and will be shared between all kde applications that can use it. Information about how to create a purposed plugin can be found on kde's gitlab: https://invent.kde.org/frameworks/purpose

A year ago I actually made a pr to kde for like a plugin that allows you to define your own uploader service, but has not went anywhere since KDE wants to integrate it into Get New Stuff and is waiting for the design team to come up with a proof of concept, so I can give it to you as an example if you want.