module_utils/ca_common: Add optional diff argument to exit_module
module_utils/ca_common: Add optional diff argument to exit_module

Add optional `diff` argument defaulting to `{ "before": "", "after": ""}`.

Signed-off-by: Mathias Chapelain <a25b9ce6392e903c28b85534d39c9f80ed302af2@proton.ch>

ceph/ceph-ansible,ceph/ceph-ansible