Support for E1810 as media player controller

[EPMatt]

The Ikea E1810, with its 5 buttons and all the different events it can fire, is a feature-rich and flexible device. Given its versatility due to its design, it is not only suitable for controlling light brightness and temperature, but works perfectly also as a media player controller.

This PR enables support for the E1810 as a media player controller (both for zigbee2mqtt and deCONZ). Actions are mapped as it follows :

• brightness_up_hold: volume up (hold, multiple steps)
• brightness_up_release: volume up (release)
• brightness_up_click: volume up (single step)
• brightness_down_hold: volume down (hold, multiple steps)
• brightness_down_release: volume down (release)
• brightness_down_click: volume down (single step)
• toggle: play/pause
• arrow_right_click: next track
• arrow_left_click: previous track

The following actions are not currently being used by this integration:

• arrow_left_hold
• arrow_left_release
• arrow_right_hold
• arrow_right_release

@xaviml are there any media player features which you think could be nice to map to those unused actions?

[xaviml]

Hi @EPMatt,

Thanks for your contribution. This is something I was thinking to do. For the moment we could leave as it is, but I would like to implement the seek position (forward and backwards) for the 2 actions left. However, to do so, I need to refactor the logic I have for the brightness and color temperature from the light, so we don't have duplicated code.

[EPMatt]

Hi @xaviml,
You're welcome! I'm happy to contribute to this cool project. :)
Yeah, track seek is a good feature to have for the controller. If needed, I could help with the refactor.