tbtc - Remove notifyDepositExpiryCourtesyCall and allow exitCourtesyCall exiting the courtesy call at term
Following a deep dive into state transitions with the client it was agreed that `notifyDepositExpiryCourtesyCall` should be removed from the system as it is a left-over of a previous version of the deposit contract.\\nAdditionally, `exitCourtesyCall` should be callable at any time.\\n```\\n/// @notice Goes from courtesy call to active\\n/// @dev Only callable if collateral is sufficient and the deposit is not expiring\\n/// @param \\_d deposit storage pointer\\nfunction exitCourtesyCall(DepositUtils.Deposit storage \\_d) public {\\n    require(\\_d.inCourtesyCall(), "Not currently in courtesy call");\\n    require(block.timestamp <= \\_d.fundedAt + TBTCConstants.getDepositTerm(), "Deposit is expiring");\\n    require(getCollateralizationPercentage(\\_d) >= \\_d.undercollateralizedThresholdPercent, "Deposit is still undercollateralized");\\n    \\_d.setActive();\\n    \\_d.logExitedCourtesyCall();\\n}\\n```\\n
Remove the `notifyDepositExpiryCourtesyCall` state transition and remove the requirement on `exitCourtesyCall` being callable only before the deposit expires.
```\\n/// @notice Goes from courtesy call to active\\n/// @dev Only callable if collateral is sufficient and the deposit is not expiring\\n/// @param \\_d deposit storage pointer\\nfunction exitCourtesyCall(DepositUtils.Deposit storage \\_d) public {\\n    require(\\_d.inCourtesyCall(), "Not currently in courtesy call");\\n    require(block.timestamp <= \\_d.fundedAt + TBTCConstants.getDepositTerm(), "Deposit is expiring");\\n    require(getCollateralizationPercentage(\\_d) >= \\_d.undercollateralizedThresholdPercent, "Deposit is still undercollateralized");\\n    \\_d.setActive();\\n    \\_d.logExitedCourtesyCall();\\n}\\n```\\n