Auto merge of #5393 - smithsps:master, r=matklad

Add target directory parameter --target-dir

Implements: https://github.com/rust-lang/cargo/issues/5308

Adds a target directory parameter, that acts in the same manner as the environment variable `CARGO_TARGET_DIR`, to the following subcommands:
- `bench`
- `build`
- `check`
- `clean`
- `doc`
- `package`
- `publish`
- `run`
- `rustc`
- `rustdoc`
- `test`