feat(cancun): Cancun features should have examples (which can also serve as E2E tests)

[david-bakin-sl]

With the Cancun upgrade (targeted: services 0.50) there should be examples of some Cancun functionality in the smart contract repo. And they can also serve, perhaps, as end-to-end tests of (some of the) Cancun functionality.

Examples would demonstrate Cancun functionality: E.g., a contract using transient storage will work (instead of fail with invalid opcode).

See HIPs 865, 866, 867, and 868 for the scope of Cancun.

See related issue #2391 in the JSON-RPC Relay repo.