API: progress protocol (#167)

Implement a protocol for progress reporting. Provides an implementation
using the existing `rich`-based progress bar, as well as a new
`ipywidgets`-based progress bar for Jupyter notebooks.

Closes: #140

Author: ntessore

.commitlint.rules.js

@@ -15,6 +15,7 @@ module.exports = {
         "mapper",
         "mapping",
         "progress",
+        "rich",
         "twopoint",
       ],
     ],