Feature Idea: create card/task from Mattermost

Summary:

1. Write a message on Mattermost, for example: /card @tom Buy cookies
2. This creates a card Buy cookies in Focalboard, assigned to Tom

This could be improved in the future with the following ideas:

3. Define a specific syntax to include additional information (content, date, board, status, priority, project, ...). For example /card @tom Buy cookies [2 chocolate + 1 nuts] would add the content 2 chocolate + 1 nuts to the card
4. A message is automatically created on Mattermost, in reply to the original message (in the same thread), providing the link to the card on Focalboard
5. If no project/category is specified, it could be automatically flagged as "to be sorted"

As far as I understand:

6. I'm not sure how all this is already the project of https://github.com/mattermost/focalboard/discussions/349
7. This feature would be the mirror feature of https://github.com/mattermost/focalboard/issues/282.

How important this is to me and why:

Importance: High

Use cases:

1. We use Mattermost extensively to manage todos. But the current plugin is not advanced enough and not transparent enough (not everybody can see all the pending tasks)
2. We discuss a topic on Mattermost, and a todo is decided: the follow-up is currently not easy, while Focalboard could provide that

Additional context / similar features: With Asana, sending an email with a specific syntax creates a card/todo in Asana.