[draft] Escrow liquidation array methods

[artdgn]

This is a gas improvements exploration PR following the audit feedback.

This adds an array method getVestingSchedules which uses only array based views on the previous contract in order to reduce the amount of external calls during the revoke loop for a worst case scenario gas test.

While this reduces the number of external calls (by using only array based methods), it only saves 240K gas (3438k vs 3683k in base PR). This is likely due to the fact that STATICCALLs to the warm addresses are actually pretty cheap (https://www.evm.codes/about#accesssets)

The code added in the getVestingSchedules is complex, branching, includes non trivial index offset calcualtions and requires adding additional tests (for all these possible edge cases and branches). It also is a dependency of the revoke method, which means that if a bug in manages to slip through, working around it will be annoying and even gas expensive.

This improvement is thus not likely to be worth to include.