get bundle from bundle image API call

[jmccormick2001]

this Issue is to request an API call be created so that we can get a bundle's contents from a bundle image, something similar to this:

func GetBundleFromImage(imageName string) (registry.Bundle, error)

then you could validate that bundle using a method added onto the Bundle such
as:

validationResults := myBundle.Validate()

also, ideally the Validate would not produce output to the logs but instead leave that to the caller to log from the results as they wish.

we also are in need of a helper function on a registry.Bundle that would let us get the list of CRs back from the CSV's alm-examples annotation, something akin to:

crList := myBundle.GetCRs()

we took a stab at creating such a function here: https://github.com/operator-framework/operator-sdk/pull/2890/files/98cfa697390d427c918470124839195d6d503a0c#diff-26ea1412bbd74151f01f483ebc6a42ef

[joelanford]

Only thing to add is that I think we also need a similar function that loads a bundle from an on disk representation.

[camilamacedo86]

Regards:

func GetBundleFromImage(imageName string) (registry.Bundle, error)

OF/API allows us to pass the path of the bundle.
Then, users can download the bundle locally and pass the path instead of the image.
IHMO we do not need this one.

we also are in need of a helper function on a registry.Bundle that would let us get the list of CRs back from the CSV's alm-examples annotation, something akin to:

@joelanford @anik120 do you think that is still a need? This issue was open for a long time ago.
If yes, wdyt about we raise a new issue only for this request in order to clarify better what should get done.
thoughts?