Add `cargo contract deploy` command

I often find myself scripting something along the lines of:

cargo contract build --manifest-path flipper/Cargo.toml
cargo contract instantiate --constructor new \
    --suri //Alice --salt $(date +%s) \
    --manifest-path flipper/Cargo.toml

We should add a deploy subcommand which is able to do both of these steps (and possible more if we think of anything else) in one go.

cargo contract deploy --manifest-path flipper/Cargo.toml

The main motivation here is that we should make common development workflows as easy as possible to do from within cargo-contract, instead of having developers make their own wrappers.

There may be other subcommand we want to streamline, but this seems like low-hanging fruit.