feat: get PieceId from PieceCid

[akronim26]

This resolves #247

[rvagg]

@akronim26 check the diff, you've inlcuded a few unrelated changes in here that are just formatting, and CI is complaining about it. Try to keep the blast-radius of your PRs minimal to avoid linting problems and to make the review process a bit smoother. Thanks for the change though, it otherwise looks good 👌 .

[akronim26]

Hey @rvagg, the lint check is failing due to a part which should not be concerned for this issue. Correct me if I'm wrong thou

[rvagg]

@akronim26 yeah, I think I agree. It's a view function, and the optimisation buys us very little (loading to memory from calldata, it has to be done even in inline assembly but it might save a couple of ops to inline it, not enough to make this function messier IMO). For now, let's just put "asm-keccak256" in foundry.toml's exclude_lints, add a trailing comment: # flagging on a view function; revisit when forge supports inline suppression

[rvagg]

awesome, good job @akronim26