Use Native Context Menu

[durasj]

Is your feature request related to a problem? Please describe.
@captbaritone proposed:

I wonder if we should expose some way for Webamp Desktop to use Electrons context menus instead of the fake ones that I made.

Describe the solution you'd like
We'll use Menu API from Electron to add the context menu via some new API. Idea for implementation from @captbaritone is

Probably the best thing to do would be for me to transition to using an internal API that matched the Electron API. Then I could just expect you to pass me a function that accepts a menu template and renders it.

Describe alternatives you've considered
I could receive an array of options and attach some callbacks for open/close but that seems a bit more complicated.