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##### SUMMARY
<!--- Explain the problem briefly below -->
The snapshot module currently only supports storage blob as a creation source, it should
supports managed disk as a creation source. 
##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
lib/ansible/modules/cloud/azure/azure_rm_snapshot.py
##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.0
  config file = None
  configured module search path = [u'/home/haiyuan/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /opt/ansible/local/lib/python2.7/site-packages/ansible
  executable location = /opt/ansible/bin/ansible
  python version = 2.7.12 (default, Oct  8 2019, 14:14:10) [GCC 5.4.0 20160609]
```
- Disk source information.
            - CreationData information cannot be changed after the disk has been created.
        type: dict
        suboptions:
            create_option:
                description:
                    - This enumerates the possible sources of a disk's creation.
                type: str
                default: Import
                choices:
                    - Import
            source_uri:
                description:
                    - If I(createOption=Import), this is the URI of a blob to be imported into a managed disk.
                type: str
    state:
        description:
            - Assert the state of the Snapshot.
            - Use C(present) to create or update an Snapshot and C(absent) to delete it.
        default: present
        type: str
        choices:
            - absent
            - present
extends_documentation_fragment:
    - azure
    - azure_tags
author:
    - Zim Kalinowski (@zikalino)
'''