The board in embed widget (from smartpicker) should be visible for users who have access to parent file

[luka-nextcloud]

Describe the solution you'd like The embed board widget (add from smartpicker) on markdown file or whiteboard file (or any file support smartpicker widget) should be visible for users who have access to this file.

Reproduce steps:

1. Login as User1
2. Create a markdown file or Whiteboard file
3. Add a Deck board widget from smartpicker
4. Share the created file with User2
5. Login as User2
6. Open the shared file

Expect: The embed board widget should show the file without any error for the User2.

Actual: The embed board widget is empty.

[luka-nextcloud]

@juliusknorr I have some ideas:

• I think we can update the existing board sharing function to allow sharing with a file beside user, group or team. When a board is shared with a file, any user has access to that file will have access to this board
• Additionally, on the board widget, we can add a button to quickly toggle sharing this board with the current editing file (md file, whiteboard file, ...). The problem is how to get the id of current editing file

[juliusknorr]

As discussed in the team call:

• When inserting a deck board in a whiteboard we should offer to share it with all participants that have access to the whiteboard
  • UI should make this implicit that this grants access to the deck board to everyone who has access to the file
• In deck we can implement this by having a file id stored with the board (as acl) which can then be used as a reference
  • For now we just list the files in the board sharing tab with the option to remove them (just as other acl rules)
  • I have some concern when checking the permissions once accessing a board, this may be rather heavy, but maybe if we only do it on access of the board it coud be acceptable