tester: dispatcher support for multi-class contracts

[James-Mart]

The CDT allowed developers to compile multiple classes into one contract by marking them with the same contract attribute. Migrating my contract to CLSDK forced me to write my own dispatcher to allow this, but it would be nice if it was natively supported.

Perhaps something like

EOSIO_ACTIONS("contractname"_n, (
                class1,
                action(sayhi, name, ricardian_contract(sayhi_ricardian))
            ),(
                class2,
                action(saybye, name, ricardian_contract(saybye_ricardian))
            ))