CLI cmds should be consistent and more testable

**What would you like to be added**:
Newly add command for bundle on PR https://github.com/kudobuilder/kudo/pull/306 introduced new approach which other commands should adopt which includes:

* it is private function (reduce exposure to what is necessary)
* it makes an io.Writer (more testable)

**Why is this needed**:
* Better encapsulation
* Better Testing
* Consistency

Start by reviewing the bundle command approach introduced in PR 306, then identify the other CLI commands that expose command functions or do not accept an io.Writer. Compare their current structure with bundle and check the existing CLI tests; done means the commands consistently use private functions and injectable output without changing their behavior.

Written by the indexing model from the issue text.