Consider versioning the environments schema

[komalali]

To prepare for future breaking changes, have you considered adding version info into the environment file, e.g:

apiVersion: pulumi.com/v1alpha1
kind: Environment
imports:
  ...
values:
  ...

[EronWright]

Something to consider regarding the concept of apiVersion, would Pulumi adopt the versioning conventions? e.g. Pulumi would introduce v1alpha2 or v1beta1 to deliver a breaking change.