Allow setting device_class "outlet" again through entity settings

[spacegaier]

Breaking change

Proposed change

For covers and binary sensors the "Show as" dropdown allows changing the device_class to whatever fits best. However, in the settings dialog of a switch entity the "Show as" dropdown controls the new switch_as_x behavior. That however means, that we lost the option to change the switch device_class.

With this PR this option is now back.

Type of change

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

Example configuration

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• 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

[zsarnett]

@spacegaier Would like to merge this before beta if you can look at the reviews. Ill merge tonight or tomorrow