Substrate: Integrate `cargo contract` extrinsic tooling into solang

[xermicus]

cargo contract offers some handy tools for uploading, instantiating and calling a contract after successful compilation. For development and testing purposes, this CLI interface is way more efficient and convenient than using the web UIs all the time. The issue right now is that it only works for ink! contracts which come with an according Cargo.toml metadata manifest. Additionally, it would be nice to have that directly available in solang. To make this work:

• Factor the relevant parts from cargo contract into a re-usable crate
• Extend the solang CLI to mimic the following subcommands of cargo contract:
  • upload
  • instantiate
  • call