ipauser: Add support for SMB attributes.

Since FreeIPA version 4.8.0 ipauser has support for smb-logon-script,
smb-profile-path, smb-home-dir, and smb-home-drive drive attributes.

On FreeIPA, these attributes are only available when modifying a user,
so if the user defined in the playbook does not exist, two calls to IPA
API are executed, a 'user_add' followed by a 'user_mod'.
(see https://github.com/freeipa/freeipa/blob/master/doc/designs/adtrust/samba-domain-controller.md

A new example playbook can be found at:

     playbooks/user/smb-attributes.yml

A new test playbook can be found at:

     tests/user/test_user_smb_attrs.yml

playbooks/user/smb-attributes.yml

@@ -0,0 +1,17 @@
+---
+- name: Plabook to handle users
+  hosts: ipaserver
+  become: false
+  gather_facts: false
+
+  tasks:
+  - name: Ensure user 'smbuser' is present with smb attributes
+    ipauser:
+      ipaadmin_password: SomeADMINpassword
+      name: smbuser
+      first: SMB
+      last: User
+      smb_logon_script: N:\logonscripts\startup
+      smb_profile_path: \\server\profiles\some_profile
+      smb_home_dir: \\users\home\smbuser
+      smb_home_drive: "U:"