treescope visualization for attribute_context

[gsarti]

Description

This PR introduces a new visualization based on the treescope library for the attribute_context CLI method.

Currently, the visualization is produced using rich using the same format for console and notebook environments:

The main limitations of this mode of visualization are:

• The context needs to be repeated for every attributed token in output_current_text, which can produce very long sequences.
• Although attribution (CCI) scores are collected for all context tokens, only a subset is shown using the attribution_std_threshold and attribution_topk arguments of AttributeContextArgs to highlight only the most salient ones.
• Default rendering of strings and numbers in color for rich, producing confusing visualizations.

The new proposed visualization is the following:

It includes:

• Foldable parameters list that can be shown upon clicking (expanded in figure)
• Long contexts are collapsed by default and can be expanded upon clicking (collapsed in figure)
• A single output sequence with color gradients representing context sensitivity (CTI) scores, with salient tokens (as selected by AttributeContextArgs.context_sensitivity_std_threshold and AttributeContextArgs.context_sensitivity_topk) allowing for expansion to visualize attribution scores for that step (using context_sensitivity_std_threshold = None performs attribution for every step).
• CTI and CCI scores are shown upon hovering context-sensitive generated tokens.
• The non-contextual alternative for the current context-sensitive token is also shown.

Details about usage:

• Shown as default representation of AttributeContextOutput objects in notebooks thanks to __treescope_repr__.
• Used as the default method to show outputs for the CLI in notebook environments with visualize_attribute_context.
• Used as the default method to save outputs to HTML in all environments if visualization is turned off.
• rich is preserved as the default when showing the visualization in console environments. If HTML serialization is also requested, the rich outputs are saved.