Abort myq homekit config when one is already setup.

[bdraco]

Proposed change

We can see myq on the network to tell them to configure
it, but since the device will not give up the account it is
bound to and there can be multiple myq gateways on a single
account, we avoid showing the device as discovered once
they already have one configured as they can always
add a new one via "+"

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

Example entry for configuration.yaml:

# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes #
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Checklist

• The code change is tested and works locally.
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  Updated and included derived files by running: python3 -m script.hassfest.
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