Added validation if someone specifies a version on a bundle

[dgannon991]

What does this change

Added a check on version numbers if specified in your porter YAML

What issue does it fix

Delivers towards #3136

Notes for the reviewer

This is just a draft to get some feedback. I intend to refactor the Lint() function and add some unit tests, but I wanted to check if I'd gone down the right route first :)

[dgannon991]

I've added some tests and done a small refactor on the bottom of Lint(). Let me know if we want to break further parts of the function out!

[dgannon991]

I think we can close this one, it was done in a different way.

[kichristensen]

Closed in favor of #3215