Add Feature to hide/reveal elements of index cards

[mjanschek]

🚩 Is your feature request related to a problem? Please describe

I'd like to control the public visibility of single elements on cards. This would allow me to hide/reveal aspects or skills of NPC (for instance when PC try to discover an aspect in fate)

✅ Describe the solution you'd like

Add a button in advanced mode to hide/expose single fields of an index card

✏️ Describe alternatives you've considered

This could be extended to index cards that are attached as sub-cards to other index cards

📄 Additional context

This would be a good option for any game system and not just Fate, I think