(cli) add 'stacks' argument for 'ddk deploy'

[malachi-constant]

Enhancement

• Add argument for ddk deploy to allow explicitly setting stacks to deploy

Usage

• ddk deploy StackA StackB

Relates

• (cli) add stack name parameter to ddk deploy #121

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[malachi-constant]

I think we need to put in some type of testing for deploy outside of just --help. Will we need some sort of dummy DDK stack to use in order to mock a deploy ?

[kukushking]

@malachi-constant looks good thanks - feel free to merge! To your question - yeah I think for a proper E2E test we would have to provide a complete dummy app (with ddk.json & app.py)... how about we just find a way to assert the cdk command is as expected, and assume cdk itself works?