feat(msp): rejected storage request triggers file clean up if needed

[HermanObst]

Problem:

File deletion from file storage are only being triggered by MutationsApplied event. This is correct for the happy paths as this event is emitted always that an msp accepted the storage request (thus it root was updated in the runtime) and now is not required anymore, either because the user wants to delete it, or the user revoke the SR.

But this leaves us with the edge case where the msp try to accept the SR (thus, it stores the file), but the transaction fails and his root is not updated on-chain. In this case, he will never see MutationsApplied event.

Solution:

Make msp react to events that inform that the SR was incomplete (StorageRequestRejected) but MSP could have sent a tx accepting it that ends up failing.

⚠️ Breaking Changes ⚠️

• StorageRequestRejected event contains two new fields: msp_id and bucket_id. leaving the new struct as follows:

        StorageRequestRejected {
            file_key: MerkleHash<T>,
            msp_id: ProviderIdFor<T>,
            bucket_id: BucketIdFor<T>,
            reason: RejectedStorageRequestReason,
        },