Detect invalid combination of call flags and execution input at compile time

[cmichi]

Follow-up to #960.

We should throw a compilation error if for cross-contract calls call_flags.forward_input() == true || call_flags.clone_input() == true while at the same time an execution input is specified. In this case the call flags imply that the execution input will never be used.

Ideally this would not be an expect(…) at runtime, but rather an error at compile time. This can be achieved by encoding the call flags in the type system, like we do for all the other cross-contract settings in https://github.com/paritytech/ink/blob/master/crates/env/src/call/call_builder.rs.