SCREENSHOTS: "Website screenshot" mode for taking screenshots ready for our website's screenshots page

[Thunderforge]

As ScummVM has supported more and more games, there is a need for ​additional screenshots for our website. Although our wiki has ​guidelines for submitting screenshots, there are a number of aspects to it (e.g. certain resolution, certain filter requirements, file naming conventions, etc) that are easy to miss.

It would be great if we could optionally enable a "website screenshot" mode that will automatically output screenshots in a format that follows our guidelines and is ready to upload to our website. One suggestion was as follows

In fact, we should have a key combination that will take a screenshot in the right resolution to show, regardless of the user configuration (I don't know if switching scaler on the fly can used for this 🤔)