feat: implement NativeTokenMaxLossEnforcer

[matallui]

What?

• Implement a NativeTokenMaxLossEnforcer caveat enforcer, which enforces that your native token balance losses do not exceed a max value

Why?

• A good example of this is when we want to enforce a simulation outcome but, more generally, it could be used to prevent certain types of attacks (e.g. red-pill attacks), by capping our max spending.

How?

• This enforcer was based off of the NativeBalanceGteEnforcer, and the logic and tests were just adapted since we're now capping the losses, rather than guaranteeing a minimum gain.

Notes

As a side note, I had proposed to the team that we also rename our current *BalanceGteEnforcer caveat enforcers to *MinGainEnforcer, since that naming more accurately describes what it enforces IMO.

[hanzel98]

Duplicate: #90