Handle flaky SimpliSafe notification registration

[bachya]

Proposed change

At times, the SimpliSafe cloud can return flaky notification data (e.g., system.notifications has notifications on call 1, then is empty on call 2, then has the original notifications on call 3). Currently, the underlying notification logic checks the currently-saved notification set against the latest notifications from the system object; because of this flakiness, this will fire duplicate SIMPLISAFE_NOTIFICATION events for old notifications.

This PR adjusts the underlying mechanism to hold onto old notification data in memory and compare incoming data against it.

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: N/A
• This PR is related to issue: N/A
• Link to documentation pull request: N/A

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
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• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

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

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[jjlawren]

Looks good!