[enhancement] etcd encryption on rest

[foexle]

Is your enhancement / feature request related to a problem? Please describe.
The secrets stored in etcd are pretty sensitive since you can provision resources on different providers that relates directly in costs.
So we need to be ensure that those secrets cannot be accessed by third party.

Describe the solution you'd like
One item to achieve this is to encrypt the etcd (encryption on rest), so the actual data store. This would at least prevent to access the data outside of the environment (hypervisor & disk level).