Add effect service to WLED integration

[frenck]

Proposed change

Adds a wled.effect service to the WLED integration.

This allows the user to finetune the effects running on the WLED light (or set the light into a specific effect state, before turning it on.

Allows controlling:

• The effect (using an effect name or ID)
• The speed of the effect
• The intensity of the effect
• Reverse the effect

Additionally, the reverse attribute has been added to the light (since I figured it would be helpful if one could see the current state if one could set it.)

Tests are added to keep the full coverage:

----------- coverage: platform linux, python 3.7.6-final-0 -----------
Name                                           Stmts   Miss  Cover
------------------------------------------------------------------
homeassistant/components/wled/__init__.py         97      0   100%
homeassistant/components/wled/config_flow.py      56      0   100%
homeassistant/components/wled/const.py            22      0   100%
homeassistant/components/wled/light.py           110      0   100%
homeassistant/components/wled/sensor.py           51      0   100%
homeassistant/components/wled/switch.py           66      0   100%
------------------------------------------------------------------
TOTAL                                            402      0   100%
Coverage XML written to file cov.xml


Results (1.83s):
      28 passed

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 automation

# Example automation
automation:
  - alias: Alarm system
    trigger:
      platform: state
      entity_id: binary_sensor.motion_buglar
      to: 'on'
    condition: []
    action:
      - service: wled.effect
        entity_id: light.wled
        data:
          effect: police
          intensity: 255
          speed: 255
          reverse: true
      - service: light.turn_on
        entity_id: light.wled

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request: Add effect service to WLED integration home-assistant.io#12461

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

[frenck]

Documentation PR created. Marked this PR ready for review.

[balloob]

should this be called effect_reverse to make it clear what is being reversed ?

[frenck]

The same can be said about speed for example.
I kept it consistent with that and the way it is used/displayed in WLED itself, just to stay close with that.

[frenck]

Rebased PR onto the latest dev to deal with the merge conflict.