Refactor current 2D renderer into single module

[arihantparsoya]

Currently p5py uses only one renderer (vispy) for rendering 2D shapes. To add for new renderers, we want to refractor all the code related to vispy into a single module.

The current idea is to create new folder in /p5 directory called Vispy2DRenderer and add the code for vispy 2D renderer into that single module.

Important classes that needs to be refactored into Vispy2DRenderer are:

• PShape
• Renderer2D