Smart Contracts: Update all `0.8.15` code to `0.8.25`

[tynes]

Since we need EIP-1153 for the interop smart contracts, we need to use a more modern Solidity compiler. By only updating some smart contracts to use the new compiler version and keeping the old versions specifically at 0.8.15, it is creating technical debt. We should update all smart contracts to the same version of solidity.

To do this safely, we will also need to create a failure mode analysis that convinces us that there are no issues. When creating the FMA, it should include anything from the solc changelog from 8.15 to latest to be aware of any bug fixes or changes that impact us.