Detect incompatible version of ink

[ascjones]

The 2.0.0 release of cargo-contract will only be compatible with 4.x releases of ink, so 3.x releases and earlier will be incompatible.

We should add a check which reads the version of the ink dependency in the contract and if it is incompatible, provide the user with a suggestion to either

1. Upgrade their contract to 4.0
2. Install an earlier 1.x release of cargo-contract

Could also provide a link to docs with a table of compatible cargo-contract -> ink -> pallet-contracts combinations.