♻️ Migration to Cairo

[bal7hazar]

Closes #28

Remaining tasks:

• [x] ERC3525 presets
• [x] ERC3525 tests
• [x] Reimplement 721 receiver
• [x] Move ERC721 into a dedicated repo
• [x] Manage clear approval (storage key)
• [x] Clean some comments and code
• [x] Integration tests
• [ ] Unit tests (postponed after the protocol migration)
• [ ] Split and merge features (draft in base module not yet tested nor include in a preset)

Notable changes:

• Create a slot in SlotEnumerable does not emit an event anymore, it must be carried by the implemeter with a dedicated event (note that mint a token emits an event according to specification, as it was before).
• The preset that will handles both SlotEnum and SlotAproval will have to call SlotAproval.transfer_value_from then SlotEnumerable._after_transfer_value_from (it replaces the trick that was in place in Cairo 0)
• Indexes are now managed starting from 0 internaly, checks are done to avoid the slot = 0 and token_id = 0 creation

[tekkac]

Actually, it might be better to have the migration in its own repo to separate and keep both Cairo Zero vs Cairo libs.