Move `InputRange` field to inside `OutputValidityProof` struct

[guidanoli]

📚 Context

As of v1.2.0, in order to execute a voucher, one has to provide the voucher fields (destination and payload) and a proof structure. This proof structure contains an OutputValidityProof field and a proof context blob.

With #42, the specific outputs fields would be abstracted away, and the user would provide the output blob instead, to be decoded by the contract itself.

With #48, the proof context blob is no longer necessary, and we, instead, use an InputRange structure to index claims for a given application.

As a result, the signature of executeVoucher would go from...

struct Proof {
  OutputValidityProof validity;
  bytes context;
}

function executeVoucher(address destination, bytes calldata payload, Proof calldata proof) external;

... to...

struct Proof {
  OutputValidityProof validity;
  InputRange inputRange;
}

function executeOutput(bytes calldata output, Proof calldata proof) external;

In the server manager gRPC interface, however, these two fields are stored separately. The node doesn't really care about their contents specifically, and would like to look at them as opaque.

✔️ Solution

After discussing with the machine and node teams, we agreed to add an InputRange field to the OutputValidityProof structure. This would also be reflected on the gRPC interfaces used by the server manager, for example.

As a result, we can remove the Proof structure from the code base, and use OutputValidityProof instead.

struct OutputValidityProof {
  InputRange inputRange;
  // the other fields...
}

function executeOutput(bytes calldata output, OutputValidityProof calldata proof) external;