Consider aligning CRD with other external-secret projects

[reegnz]

There are multiple projects that try to do the same thing conceptually, with CRD-s very similar to this project:

• https://github.com/godaddy/kubernetes-external-secrets
• https://github.com/ContainerSolutions/externalsecret-operator
• https://github.com/cmattoon/aws-ssm

Consider unifying efforts to provide a Common API (eg. CRD) for sourcing secrets into kubernetes.

Ongoing discussion:

• https://github.com/godaddy/kubernetes-external-secrets/issues/47

[ecout]

Most of all we need secret versioning support and secret map/plain text support. Consider those two reasons to think of a merge.