Add support for multi-level lists

[SELFEMO]

Clear and concise description of the problem

Would like to be able to create folders again for categorization in the subscription feed list or category list.

Suggested solution

Add support for secondary lists or multi-level lists. Or modify it to a folder-based management format.

Alternative

No response

Additional context

No response

Validations

• [x] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• [x] This issue is valid

[linear[bot]]

FOL-1805 Add support for multi-level lists