modules: Add _info modules

modules: Add _info modules

Validate modules test fails with:

Argument state includes get, list or info as a choice.
Functionality should be in an _info or (if further conditions apply) _facts module.

on modules ceph_crush_rule and ceph_key

With Ansible 2.8 and onwards best practice requires that modules
gathering info to be put in a separate module named _info[1]

[1]https://docs.ansible.com/ansible/latest/dev_guide/developing_modules_general.html#creating-an-info-or-a-facts-module

Signed-off-by: Teoman ONAY <tonay@ibm.com>