Re-export `scale` and `scale-info` from `ink` entrance crate

[cmichi]

ToDo's

• #[storage_item] should be adapted to use Encode and Decode and type-info with crate prefixes. Same for Andrew's Events 2.0 macros.
• Create ink::Encode, ink::Decode, ink::Codec and re-export scale::{Encode, Decode, Codec}.
• Remove check for compatible scale versions in cargo-contract.