Decode Liquity events happening trough a DSProxy

[yabirgb]

Problem

Currently we decode direct interactions with liquity contracts but it doesn't work properly when interacting trough a DSProxy. This is the case for many users, for example for people using DefiSaver. An example of such transaction is

https://etherscan.io/tx/0xdac8d9273a17b00fb81e89839d0c974e393db406a641552051419646b902c4b3

What needs to be done

Adjust Liquity decoders to work with DSProxy contracts