Moves image_info from cloud to proxy object

This makes image_info compatible with new sdk version
- This patch changes get_image (which is a cloud object method) to image.get_image (proxy object method)
- image.images accepts **query which is a dict object. So this patch changes the args passed to a dict. If properties is not specified it passes an empty dict.
- updates the documentation to reflect the actual returned parameters
- adds a ci test to list all images without specifying image name or property and assert no field is missing
- changes openstack_image to image in ansible return value

Change-Id: Ibf934568f069c305747fc24fbb22ce3fc095286c

ci/roles/image_info/tasks/main.yml

@@ -0,0 +1,11 @@
+---
+- name: List all images  # This will list at least the default cirros image of devstack
+  openstack.cloud.image_info:
+    cloud: "{{ cloud }}"
+  register: image_list_result
+
+- name: Assert fields
+  assert:
+    that:
+      - item in image_list_result.images.0.keys()
+  loop: "{{ expected_fields }}"