Add DD for render_pipeline.rs and paint.rs

[nazmulidris]

Similar to https://github.com/r3bl-org/r3bl_rs_utils/blob/main/docs/dd_editor_component.md create a new DD for render pipline and painting:

1. how does the render pipeline work w/ renderop
2. how are different terminal backends implemented
3. how is the cursor data managed by TWData
4. how is ansi text content clipped
5. how is plain text content clipped
6. how is unicode "jumping" managed to provide the same experience across various terminals & os matrix *using unicode_width as the source of truth for how (display) wide a grapheme cluster is