IVS enclave image

An IVS image is an enclave image that consists of the input-verification-client and input-verification-executable. The Market Creator needs to code and build the input-verification-executable as the first step and then copy-paste it into a template codebase to build the enclave image. The input-verification-client is a simple client that takes some runtime variables like RPC URL and is already part of the template codebase.