🗞️ feat: add ONFT721Enumerable to onft-evm

[St0rmBr3w]

In this PR:

This PR introduces the ONFT721Enumerable contract to the onft-evm library, extending the functionality of ONFT721Core by integrating OpenZeppelin's ERC721Enumerable. This enhancement allows for enumeration of tokens owned by an address and all tokens within the contract, providing developers with advanced querying capabilities for ONFTs.

Key Features:

• Extension of ONFT721Core with ERC721Enumerable:
  • Enables token enumeration features such as tokenOfOwnerByIndex and tokenByIndex.

Usage Considerations:

• Gas-Implications Updates to Data Structures:
  • Implements additional mappings (_allTokens, _allTokensIndex, _ownedTokens, _ownedTokensIndex) to track tokens globally and per owner.
  • Requires updating these data structures during minting, burning, and transferring tokens:
    • Minting: Adds token IDs to _allTokens and _ownedTokens.
    • Burning: Removes token IDs from both _allTokens and _ownedTokens.
    • Transferring: Updates _ownedTokens for both sender and recipient.

For projects sensitive to gas costs, careful evaluation is necessary to determine whether the enumeration features outweigh the added costs.