Splitters assume variables have been cached

[Evert0x]

Splitters read balances from cachedChildOneBalance and cachedChildTwoBalance in deposit and withdraw actions (#24)

But there is no enforcement that the latest balances are actually cached.

Task

Still WIP

• Make the default value of the cached... variables isn't 0 but type(uint256).max as the real value of a underlying node can be 0.
• On the start of deposit and withdraw actions make sure the cached... variables are not their default values
• Expire the cache in the deposit and withdraw actions to be 100% sure the cache variables are reset to their default values

Challenge

A strategy can be visited multiple times based on the splitter used SEE:

sherlock-v2-core/test/strategy/splitters.js

Line 832 in e492f04

// Double DEPOSIT on one!

Expiring the cache at the end of a deposit or withdraw call will make the second visit (on deposit or withdraw) revert