##### SUMMARY
win_domain_user always returns changed if a password is specified.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
win_domain_user

##### ANSIBLE VERSION
```paste below
ansible 2.8.1
  config file = /etc/ansible/ansible.cfg
  configured module search path = ['/home/user/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3.7/site-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.7.3 (default, Mar 26 2019, 21:43:19) [GCC 8.2.1 20181127]
```

##### CONFIGURATION

##### OS / ENVIRONMENT

ArchLinux

##### STEPS TO REPRODUCE
```yaml
- name: Set AD User Password
      win_domain_user:
        name: '{{ user_name }}'
        password: '{{ password }}'
        state: present
- name: Set AD User Password again
      win_domain_user:
        name: '{{ user_name }}'
        password: '{{ password }}'
        state: present
```

##### EXPECTED RESULTS
The 2nd task to show as not changed.

##### ACTUAL RESULTS
The 2nd task shows as changed, even though the password was already set.
description:
      - A dict of custom LDAP attributes to set on the user.
      - This can be used to set custom attributes that are not exposed as module
        parameters, e.g. C(telephoneNumber).
      - See the examples on how to format this parameter.
    type: str
    version_added: '2.5'
  domain_username:
    description:
    - The username to use when interacting with AD.
    - If this is not set then the user Ansible used to log in with will be
      used instead when using CredSSP or Kerberos with credential delegation.
    type: str
    version_added: '2.5'
  domain_password:
    description:
    - The password for I(username).
    type: str
    version_added: '2.5'
  domain_server:
    description:
    - Specifies the Active Directory Domain Services instance to connect to.
    - Can be in the form of an FQDN or NetBIOS name.
    - If not specified then the value is based on the domain of the computer
      running PowerShell.
    type: str
    version_added: '2.5'
notes:
  - Works with Windows 2012R2 and newer.
  - If running on a server that is not a Domain Controller, credential