Reasons for using regular approvals instead of permit2:
- More simplicity, simpler setup
- Unfortunately we won't be able to "expire" approvals, which is a risk we may be okay with taking - since one advantage of this is that we will be able save on gas by not approving the reactor every single time (is this our intention?)
TODO:
- Do we really need input tokens to pass through our router?
- Handle native ETH (double check how this is transferred in the reactor)