Wrong price used in release funds

[zajck]

The release funds method always uses the original offer price:

https://github.com/bosonprotocol/boson-protocol-contracts/blob/9ed49d780f04b2f168001f72d6c09f5fc94818b7/contracts/protocol/libs/FundsLib.sol#L132

This is incorrect for offers with price discovery and offers with sequential commit since the last price is likely to be different from the starting price.

First the test suite should be updated and then the contracts should be fixed to release the correct amount.

[zajck]

This introduces another constraint - each secondary price should be at least equal to buyer cancelation penalty to work when the final state is canceled.