Fix verify and verify-attestation output flag

[josedonizetti]

There are a few things on this PR.

1 - improve documentation, listing the possible options for -output -> '(json|text)'
2 - fix existing behavior, where -output is actually ignored, using always text, even though the documentation says the default is json.

A couple questions:

1 - I think it makes more sense to rename this flag to -format, instead of -output considering the options (json/text).
2 - The current default is text, but fixing this to follow the documentation, it becomes json, but I think text looks better on the command line.

wdyt?

[dlorenc]

1 - I think it makes more sense to rename this flag to -format, instead of -output considering the options (json/text).

Could we keep output as an alias? I think you're right, but would prefer not to break stability right after 1.0 :(

[josedonizetti]

@dlorenc What do you think about merging as is? It fixes the hardcoded option, allowing the user to choose a format, and I can follow up with a different PR for a new format flag alias of output.

[developer-guy]

@dlorenc What do you think about merging as is? It fixes the hardcoded option, allowing the user to choose a format, and I can follow up with a different PR for a new format flag alias of output.

yeah make sense to me, I'll approve the PR as is, as you said maybe you can create another PR for the alias thing, PTAL @dlorenc

[developer-guy]

LGTM