Contract Requests doesn't check if requester already has requests

[br-arruda]

https://github.com/brunoarruda/PGC-Prototype-Client/blob/22d9e195eb2a29f6a40d761a195a3418e3b0fde1/src/main/resources/solidity/SmartDCPABERequests.sol#L58

There must be a check here to not allow multiple entries of a same requester on the array.