Add cargo contract deploy command

[HCastano]

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.

[ascjones]

One issue to decide with this is how to deal with all the build options. We can either

1. Accept all the arguments of both build and instantiate to the deploy command, though there may be some clashes e.g. --manifest-path.
2. Restrict the arguments allowed for build i.e. can only specify --release or --debug, all other options are default or inherited (in the case of --manifest-path)