Add purely RzIL listing of the function

Is your feature request related to a problem? Please describe.

Show the RzIL text of the function, just like we have already for disassembly

Describe the solution you'd like

Ideally, it would be awesome to be able to locate Disassembly and RzIL widgets side-by-side

Describe alternatives you've considered

Option/hotkey to switch between assembly and RzIL inside the Disassembly widget

Additional context