fix: keep escaping closure attribute in mocks

[Kolos65]

Up until this point, all attributes including @escaping were removed from function parameter types in the generated mock implementation to allow using them in other places than parameter positions. (ex.: enum cases)

This however is wrong when generating the producer resolver, that uses the function parameter types at closure parameter positions and needs to mark potential closure type parameters @escaping.

Also, inout was previously removed from closure parameters in the above process. This PR keeps it and adds support for inout types in willProduce clauses.