Tasks: allow passing arguments to tasks

Example:

const hello = project.addTask('hello');
project.exec(`echo Hello, $@!`);

$ pj hello "world"
Hello, world!

Questions

1. The $@ notation is just an example. Perhaps it would be easiest to support this by injecting the arguments into environment variable(s).
2. Would be amazing if tasks could leverage yargs’ engine to parse switches.
3. Should tasks also “register” positional arguments and switches for yargs?

[pgollucci]

Another use case yarn deploy --profile damadden88

[Chriscbr]

Maybe as an escape hatch for all tasks, we could allow extra arguments to be passed automatically after a “–”, as in:

const deploy = project.addTask('deploy');
deploy.exec(`cdk deploy`);

$ pj deploy -- --all
... runs 'cdk deploy --all'

And meanwhile, more fancy argument-insertion could be allowed like so:

const lint = project.addTask('lint');
lint.exec(`eslint --ext .ts,.tsx $@ src tests`);

$ pj lint --fix -- build-tools
... runs 'eslint --ext .ts,.tsx --fix src tests build-tools'