Add functionality to keystone to act as a
certificate transfer provider.
Add actions to add, remove, list CA certs
to keystone.
Add Certificate Transfer requires handler
in ops_sunbeam. Update keystone_auth section
cafile option if certificate is available
in receive-ca-cert relation.
Update metadata.yaml for keystone and rest of
k8s charms.
Change-Id: I9c800e8f8a0c9197b195331be7b445bafe794780
bd057784d5