Companion for Radio France od Valdr687

Add easy download and keyboard shortcuts for Radio France website.

The shortcuts are:
Space : Pause and resume
⬅️ : -10s
➡️ : +10s
⬆️ : Increase volume
⬇️ : Decrease volume

Download the podcast's file (mp3 or m4a) by opening the extension's popup and by clicking on "Télécharger podcast"

Should work for every radio, except "Mouv'" that, for now, has some malfunctionning buttons.

> Based on Radio France Ultimate by leoCottret
> Github : https://github.com/Valdr687/Companion-for-Radio-France