Upgrade filecoin.sol libs dependency

[shrenujbansal]

As part of this, remove items in contract code which were a stop gap due to initial lack of tooling in the library. Specifically

• Big Int to uint conversions and vice versa
• getDelegatedAddress logic correction

[Pfed-prog]

bigIntToUint

Assumption on Byte Size: The conversion from bytes32 to uint256 assumes that the contents of bigNumUint.val can safely be interpreted as a positive uint256. If neg is true, the code does not handle negative numbers, so this could lead to incorrect behavior or unexpected results if the original CommonTypes.BigInt represents a negative value.

Data Integrity: Ensure that bigInt.val does not represent a value larger than what can be stored in a uint256 (i.e., more than (2^{256} - 1)) to prevent overflow when converting from bytes32.

Memory Management: Since bigInt is passed as memory, it won't incur storage costs, but it is good to be cautious when dealing with larger structures. Make sure the operations stay efficient.

Best Practices: Consider also handling cases explicitly for negative numbers or larger values to make the function more robust. You might want to include require statements to check the validity of bigInt before proceeding with the conversion.