EqualizerView: Create custom profiles + Global feature improvements

This merge request brings an addition to the Equalizer with:

• The ability for users to create and store custom equalizer profiles.
• The proper custom equalizer profile is now applied when the playback starts if needed (for both the Video and Audio players).
• Users can now edit the custom profiles' section of the presets table view and delete and rename the custom profiles previously created by swiping to the left and selecting the proper action.

This merge request also brings some improvements to the already existing Equalizer features with:

• The save button that is now simply hidden/displayed when necessary by using an animation and its isHidden property.
• The equalizer's values that are reset to the current selected profile when the playback stops.

Screenshots

Closes #502 (closed)