Sherlock [1]: Fix casting & overflow issues

[Oighty]

This PR refactors the codebase to use uint256 values for all token amounts except in the bid storage for the EMPAM module so we have efficient loads & storage for the decrypt and settle process.

Fixes:

• https://github.com/sherlock-audit/2024-03-axis-finance-judging/issues/181
• https://github.com/sherlock-audit/2024-03-axis-finance-judging/issues/204

Tasks

• [x] Refactor code and get to compile
• [x] Refactor tests
• [x] Update tests with minor logic changes due to size check and no longer dealing with overflows