Support for attribute config and several bug fixes

Feature
Let the slider control an attribute
Light:

• brightness_pct (default)
• brightness
• color_temp
• hue
• saturation

Cover:

• position (default)
• tilt

Fixes

• Apply color_temp on slider for lights
• Fix lights that behave as switches (color_mode = onoff)
• Toggle option now toggles instead of setting value to max