Add or remove proof requirements when a request contract’s state changes. When a request sale has completed (for a slot), the host who purchased that slot now must provide regular proofs for the data they are contracted to hold. This is now enforced by adding the slotId to the HashSet of Ids for which to require proofs. When a request has been cancelled (not all slots were filled before the request expired), proofs no longer need to be provided and the slotId is removed from teh HashSet.
Add `isCancelled` and `isSlotCancelled` checks to query the contract state without relying the on the state context variable in the contract. Because contract state can only be updated in a transaction, and the client withdrawing funds is responsible for changing the contract state to “Cancelled”, the `isCancelled` and `isSlotCancelled` functions were introduced to check the state regardless of whether or not the client had already withdrawn their funds.
When a request for storage times out (not enough slots filled), the client will initiate a withdraw request to retrieve its funds out of the contract, setting the state of the request to RequestState.Cancelled. The client will also emit a RequestCancelled event for others to listen to (ie hosts will need to listen for this event to withdraw its collateral).
Add unit test that checks for emission of RequestCancelled after request is purchased request expires.
Update dagger-contracts dependency to commit that holds the changes supporting withdrawing of funds.
- rename `ContractId` to `SlotId`
- add `RequestId`, `PurchaseId`, `Nonce` types as aliases of `array[32, byte]`
- rename `Proving.contracts` to `Proving.slots`
- change signatures of `isSlotCancelled` and `isCancelled` to use `SlotId` and `RequestId` types, respectively.
- change all references to `RequestId`, `SlotId`, and `PurchaseId`
