feat: fraxtal assets

[pegahcarter]

Questions:

• Should interfaces/ dir reside inside fraxtal/, within the respective token dir, somewhere else, or not at all?

Note that the contracts to be audited by Zellic are not yet included in this repo. I will be adding them separately post-audit once any necessary changes are applied.

Needs your approval here @tom2o17 @FortisFortuna

[FortisFortuna]

Questions:

• Should interfaces/ dir reside inside fraxtal/, within the respective token dir, somewhere else, or not at all?

Note that the contracts to be audited by Zellic are not yet included in this repo. I will be adding them separately post-audit once any necessary changes are applied.

Needs your approval here @tom2o17 @FortisFortuna

I think if it is an unrelated "helper" interface for something external to the project (like IERC20) we can put it in the shared interfaces folder, but if it is an interface of something defined in the project, put it in that respective folder. Open to other suggestions.

[pegahcarter]

I see what you're saying. Similar to OZ where there's contracts/token/ERC20/ERC20.sol and contracts/token/ERC20/IERC20.sol and a base interfaces/ dir with standalone interfaces. That makes sense. If @tom2o17 has no objections here I'll go with that.

[tom2o17]

LGTM

Agree with the convention put forth by @FortisFortuna, for the interface convention