Add Shortcuts support

[cyanzhong]

To enhance https://github.com/MarkEdit-app/MarkEdit/wiki/Text-Processing further.

[leits]

Hi @cyanzhong,
I'm Andrii, a https://github.com/leits/MeetingBar maintainer.
Found your pull request with shortcuts implementation in your macOS app. Great work!
I've spent several days trying to make an integration for MeetingBar. Could you help me? How did you get these intents to appear in the Shortcuts app?

[cyanzhong]

Hi @leits, thanks for reaching out.

In fact, I don't think you need to do anything special, if you just want to have them shown alphabetically in the Shortcuts app. The system scans all your AppIntent implementations and does that for you. The only thing to take care of is that you probably want to make sure there's only one MeetingBar when you debug, because Shortcuts might be randomly selecting one, which can be the one without Shortcuts support. I don't know if there's a better way other than removing all other versions, please let me know if you figured out.

To have App Intents categorized, you can leverage categoryName in IntentDescription, I haven't done that because I only have a few intents.

[leits]

Thank you @cyanzhong!
Your answer told me I was on the right track and I started looking at possible problems outside the code.
It turned out that the shortcuts did not appear for me, because I had the other version of my app (installed from the AppStore). They appeared when I deleted it and rebuilt the dev version in Xcode!

Thanks for your help and contribution to open source 🙌