Replacement feature for variables prompting in the values feature

[brandtkeller]

Variables will be removed in the v1beta1 schema of packages. Users will need to migrate to the use of package values.

As such, one area that is not currently planned for parity is the ability to prompt the user to provide required inputs. There are ways to circumvent this issue by requiring values with the schema but not including them such that deploy schem validation fails - but this doesn't rule out additional features that could exist to make this feedback loop more intuitive and clear.

Open to all thoughts and opinions.