Equalizer: rework the UX/UI from scratch

Description

The current equalizer's UX/UI is really poor and the code is barely manageable at this point. The whole EqualizerFragment class should be rewrote from scratch.

Expected behavior

Enable switch should disable all the views when un-checked
Presets should be presented differently (as the Spinner state is a mess to manage)
We should not use the sharedpreferences to store the custom sets and use the room DB instead

Screenshot / video

App mode

Smartphone