macOS Widget (extension) signing support

[rtharston]

Hello,
I just added a widget extension to our macOS application and got the following error in AppCenter when I tried to build:

I then tried adding a provisioning profile for the extension and didn't see any way to add one.

Some searching led me to issue #48, which lead to this blog post announcing support for iOS app extensions that shows exactly what I need, a place to add additional profiles.

Could we please get that same support for macOS extensions so we can build our widget without resorting to unsafe hacks or moving to another build platform?

Thanks.