Add the ability to just inspect the available variables on a package

[GemmaClements]

Is your feature request related to a problem? Please describe.

There are times when it would be useful to view all the possible variables in a Zarf Package that could be overridden such that these can be automated into documentation.

Whilst zarf package inspect definition will offer the full definition there are some occasions where just listing the variables could also be beneficial and more concise to read.

Describe the behaviour you'd like

• Given you run zarf package inspect variables
• When command succeeds
• Then it should display all the possible variables and descriptions so and end user could select overrides that maybe required in their configuration at deployment point if required

Describe alternatives you've considered

We have previously tried zarf package inspect definition and then reading the yaml and extracting these into markdown tables but this becomes quite challenging if some variables are matched directly to paths for values.

Additional context

Add any other context or screenshots about the feature request here.

[brandtkeller]

Agree on the UX around improving discoverability about deploy-time configuration optionality.

I think we'll want to design the workflow around package values as variables will be removed in the v1beta1 schema version.

We expect that the v1beta1 schema is available in the coming month and hope to begin surfacing deprecations around the current schema (v1alpha1) and the implication of such thereafter.

Otherwise we have heard similar requests - how do we make the UX better around deploy-time configuration AND values moving forward.