Remove hidden property from fibaro integration

[frenck]

Breaking Change:

Entities from the Fibaro integration were hidden in Home Assistant if they were hidden in Fibaro, which is no longer the case. This could affect automations that relies on the hidden state attribute of entities created by this integration.

Description:

Removes the hidden property from the Fibaro integration.

The hidden property dates from the pre-Lovelace era, where entities themselves determined if they were hidden or not. Besides, a device hidden in Fibaro, could be shown in the Home Assistant UI, which this change allows for now.

(recap: A device hidden in Fibaro, should not be the control on if a device is shown/hidden in Home Assistant).

Pull request with documentation for home-assistant.io (if applicable): n/a

Example entry for configuration.yaml (if applicable):

fibaro:
  gateways:
    - url: http://192.168.1.161/api/
      username: your_username
      password: your_password

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist

[MartinHjelmare]

Hidden is part of the entity state attributes if true, so we should mark this a breaking change.

[frenck]

Added breaking change section.