Instance methods should be rejected if used as static methods

[anton-trunov]

The following fails at the FunC stage, but should be rejected by the typechecker

message Hello {
    name: String
}

contract Test {
    receive() {
        message(MessageParameters{
            to: sender(),
            value: 0,
            mode: SendRemainingValue,
            body: Hello.toCell(), // `toCell` is mistakenly used as a static method here
        });
    }
}

Uncovered by @Gosunov