[Feature Request] Notify Merchant When A Contract Has Been Cancelled

[Kuosumi]

When a user cancels a contract, the 1 XSN collateral is generally spent which voids the contract.

It would create a better user experience for TPoS merchants to notify them that this contract is no longer valid so they can close the server and update their list.

In addition, if we are able to also notify the merchant when funds are moved out of a TPoS as this can often be the case that the contract is closed & the staker has left their 1 XSN collateral so it appears if the contract is still active but it's not.

At present, a merchant needs to check all their various TPoS contracts to get an updated value/ to see which one has changed.