Idempotency issues

[iamhopaul123]

Currently many of our subcommands are not idempotent, which means that they can throw errors if users have deleted some of the resources in advance. Therefore, for better user experience we need to make every subcommand idempotent if possible. Here is a list of the subcommands with idempotency issues:

• app init (Make "app init" idempotent #552)
• env init (env init workflow can't write env SSM entry if user cancels during active deployment #301)
• env delete(Make "env" subcommands idempotent #660)
• pipeline delete
• pipeline init

*The list might not cover all subcommands with idempotency issue. If there's more feel free to add to it.