feat(core & ui): add audio volume control through arrow keys

[Vija02]

Adds the ability to control the volume of audio through arrow keys (up and down). This will update the volume by 10% increments.

Solves #320 partially.

There's no visible UI element yet since I think some discussion on how that should look like before implementing would be good.
However, this will at least give people the option to control the volume if they know the button to press.

[aarthificial]

I'd imagine the volume slider to appear above the sound icon when hovering it:

Let me know if you'd be interested in implementing it in the context of this PR.

[Vija02]

Updated your changes.

UI: Hmm, the only thing stopping me would be implementing the popover component which doesn't seem to exist in the project yet. Maybe we can use something like Popper?

Let's get this PR merged and I'll make a separate PR if I get around to it.

[aarthificial]

Thanks for the PR!

I think Popper would be a bit of an overkill for this.
This element is more like a dropdown and since overflow is not disabled in this control bar, you should be able to easily position the slider with position: absolute:

(Here's a div I put inside of the volume button with position: relative)

[jmaen]

Are you currently working on this @Vija02 ?

[Vija02]

@jmaen No I'm not