Add support for mentions (viewing, sending, receiving notifications, etc.)

[sabogalc]

macOS versions Big Sur and up have support for iMessage mentions, which allows you to mention your contacts by name in a message. A mentioned name shows up in boldface and notifies the contact that they were mentioned. Below are some screenshots. Additionally, below is some documentation on sending a message with a mention. https://docs.bluebubbles.app/private-api/imcore-documentation#sending-a-message-including-subject-effect-mention-and-or-reply As well as a pull request for BlueBubbles that adds support for mentions. https://github.com/BlueBubblesApp/bluebubbles-helper/pull/10

[tagavari]

Thank you for opening this issue! AirMessage doesn't support interfacing with private system frameworks, but I'll keep this in mind for if / when this becomes the case.