Fix invariants in CI

[QGarchery]

Working on top of #595.

This PR:

• restores invariants in the CI
• fixes a rounding direction issue when finding a bound for liquidate repaid shares
• fixes using an incorrect market when finding a bound for liquidate repaid shares (see d4d5e56)
• separates dynamic invariants from static invariants. Static meaning that it's all at the same block and price does not change (see the added function selectors in DynamicInvariantTest.sol)
• removes weights of selectors. How often a function is expected to be called is not a good indicator of the contribution it could have in bugs and hacks