##### 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:
      - C(yes) will prevent the user from changing their password.
      - C(no) will allow the user to change their password.
    type: bool
  firstname:
    description:
      - Configures the user's first name (given name).
    type: str
  surname:
    description:
      - Configures the user's last name (surname).
    type: str
  company:
    description:
      - Configures the user's company name.
    type: str
  upn:
    description:
      - Configures the User Principal Name (UPN) for the account.
      - This is not required, but is best practice to configure for modern
        versions of Active Directory.
      - The format is C(<username>@<domain>).
    type: str
  email:
    description:
      - Configures the user's email address.
      - This is a record in AD and does not do anything to configure any email
        servers or systems.
    type: str
  street: