Allow environment variables to replace catalog file data tokens.

[kendavis2]

When a catalog file, cstore.yml, is embedded inside a container, a new image is required to change the files[x].data like, AWS_S3_BUCKET. This can cause migrating between AWS accounts or S3 buckets to invalidate past container images preventing deployments of past versions in the new environment.

Allowing the files[x].data to be populated from exported environment variables will increase the portability of existing container images.

context: cstore
files:
- path: service/dev/.env
  store: aws-s3
  type: env
  data:
    AWS_S3_BUCKET: ${S3_BUCKET}
    AWS_STORE_KMS_KEY_ID: ${KMS_KEY_ID}
  tags:
  - service
  - dev
  vaults:
    access: env
    secrets: aws-secrets-manager
  versions: []

[dalmena]

Very elegant solution

[kendavis2]

May close this PR since this functionality is supported in https://github.com/dabblebox/stash.