Fix Synology NAS discovered multiple times

[Quentame]

Proposed change

Adding all possible NAS MAC address to the config entry to abort the SSDP step if the serial (which is a MAC) is in configured MACs.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fix Synology DSM discovery: flow unique_id issue? #34888 + fix Synology DSM discovery: KeyError: 'host' #34954 + fix Synology DSM discovery has found 2 separate copies of my NAS #34581
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• Untested files have been added to .coveragerc.

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

[Quentame]

I could not test it on my network @bdraco

May you ? (with 2 eth connected to your NAS)

[bdraco]

Added for debugging

_mac_already_configured
....
        _LOGGER.debug("Checking mac: %s, existing macs: %s", mac, existing_macs)

The mac that comes from discovery has no -s

2020-05-02 23:32:35 DEBUG (MainThread) [custom_components.synology_dsm.config_flow] Checking mac: 001132BE0C99, existing macs: ['00-11-32-BE-0C-99', '00-11-32-BE-0C-9A']

[bdraco]

Requesting changes so I see the ping its ready again

[bdraco]

Restarted. The discovery dupe is gone.

Deleted and restarting again to make sure discovery still works

[bdraco]

Confirmed discovery still works.

One more restart and then I'm update production

[bdraco]

All good, not rediscovered when setup from discovery and restarted

Production update went well.

Now doing a configure as localhost and restart to make sure it doesn't appear in discovery

[bdraco]

Confirmed not rediscovered when setup as 127.0.0.1 and discovery comes from the network ip

[bdraco]

Nice job on this!