Refactored baremetal_node and baremetal_node_info modules

Added integration tests for both modules. They will not run in CI atm,
because we do not have Ironic enabled in our DevStack environment.

Sorted argument specs and documentation of both modules.

Refactored both modules to be subclasses of OpenStackModule class.

Renamed baremetal_node_info's module attribute 'node' to 'name' and
added the former as an alias to be consistent with other *_info
modules.

baremetal_node_info will no longer fetch port and portgroup details
because this requires extra api calls for each node. Users can use
the baremetal_port module to retrieve ports for each node on demand.

Refactored code for constructing node updates in baremetal_node module
which allowed us to drop the dependency on Python module jsonpatch.

Deprecated baremetal_node's skip_update_of_masked_password attribute.
Updating or even specificing passwords for nodes has not been
supported for a while now, rendering the attribute useless.

Renamed baremetal_node's module attributes 'chassis_uuid' to
'chassis_id', 'uuid' to 'id' as well as suboptions of
'properties' to match openstacksdk. Added the previous attribute
names as aliases to keep backward compatibility.
Marked nics attribute in baremetal_node as not updatable.

Changed baremetal_node module to return attribute 'node' only when
state is present. It will return no values (except Ansible's default
values) when state is absent. Previous return value 'uuid' can be
retrieved from node's dictionary entry 'id'.
The non-standard return value 'result' has been dropped because its
content can easily be reconstructed with Ansible's is changed check.
The non-standard return value 'changes' has been dropped because it
was only returned on updates, has no known uses and can easily be
reconstructed in Ansible by comparing the returned node dictionary
with a copy of a previous node dictionary.

Module baremetal_node_info will no longer fail when no node with a
matching id or name or mac could be found. Instead it will return
an empty list like other *_info modules.

baremetal_node_info's return attribute 'baremetal_nodes' has been
renamed to 'nodes' to be consistent with other modules. The former
name will keep to be available for now to keep backward
compatibility.

Both modules convert their return values into dictionaries without
computed (redundant) values. They do not drop values such as links
anymore though, because we do not withhold information from users.

Updated DOCUMENTATION, EXAMPLES and RETURN docstrings in both
modules.

Dropped deprecated ironic_url attribute from DOCUMENTATION docstring
in baremetal_info. Dropped wait attribute from DOCUMENTATION because
its docstring will be added via documentation fragment.

Kept timeout attribute in DOCUMENTATION and argument_spec because
it has a high(er) default value, to account for long provisioning
times, than what e.g. the generic doc fragment specifies.

Change-Id: If3044acf672295e9b61fa60d0969f47cd06dfdeb