Abstract rendering process into `Renderer` ADT

[a-lemus96]

Abstract the rendering process into an ADT dedicating a separate file called renderer.py. Meet the following criteria:

• [x] Perform initial interface design
• [x] #41
• [x] #43
• [ ] #61

[a-lemus96]

The initial designed goes as follows:

Attributes:

• estimator object
• step counter for keeping the estimator updated

Methods:

• render_rays
• render_poses for rendering either one pose or multiple poses for video rendering
• step for updating estimator parameters
• Functions related for rendering using estimator process