Fix edge case in mocked relayer #67
Description
Similarly to what was done at this commit : zama-ai/fhevm@4a844a8
To handle the case where two requestIDs are equal, but one correspond to a failing callback but not the other one, the array toSkip should track the unique global oracle counter, instead of the dapp-specific request id.
Also should add the same test TestAsyncDecryptMultiContracts in fhevm-mocks repo to be future-proof.